A short analysis of some of the narrations / opinions regarding this subject
There are several theories surrounding the circumstances of the death of the Messenger of Allah ﷺ among our scholars: that he was poisoned by the Jewish woman at Khaybar, that he was poisoned by Aisha and Hafsa, or that he died a natural death because of lack of convincing evidence for the former theories. In this article I will shed some light on some of the narrations used in this discussion. Specifically, I will expose the remarkable weakness of those narrations which accuse Aisha and Hafsa. Some of the views of the scholars will also be presented for comparison.
Shaykh al-Saduq (d. 380 AH)
واعتقادنا في النبي صلى الله عليه وآله وسلم أنه سم في غزوة خيبر، فما زالت هذه الأكلة تعاده حتى قطعت أبهره فمات منها.
And our belief concerning the Prophet ﷺ is that he was poisoned during the expedition of Khaybar. The poison continued to be noxious to him until it cut his aorta and then he died from its effects.Al I’tiqadat, pg 97
Shaykh al-Mufeed (d. 413 AH)
We are not certain what Shakh al-Mufid believed. On one occasion he seems to indicate that the Prophet ﷺ was not killed. In reply Shaykh al-Saduq’s statement above, Shaikh al-Mufid writes:
فأما ما ذكره أبو جعفر – رحمه الله – من مضي نبينا والأئمة – عليهم السلام – بالسم والقتل، فمنه ما ثبت، ومنه ما لم يثبت، والمقطوع به أن أمير المؤمنين والحسن والحسين – عليهم السلام – خرجوا من الدنيا بالقتل ولم يمت أحدهم حتف أنفه، وممن مضى بعدهم مسموما موسى بن جعفر – عليه السلام – ويقوى في النفس أمر الرضا – عليه السلام – وإن كان فيه شك، فلا طريق إلى الحكم فيمن عداهم بأنهم سموا أو اغتيلوا أو قتلوا صبرا، فالخبر بذلك يجري مجرى الإرجاف، وليس إلى تيقنه سبيل.
As for what Abu Ja‘far (rah) mentions of the death of our Prophet and the Imams (peace be upon them) by poison or murder, some of this is confirmed as fact and some not. What is confirmed is that the Commander of the Believers, al-Hasan and al-Husayn (peace be upon them) departed from this world by murder, none of them died a natural death. Musa ibn Ja‘far (as) was killed by poison.Tasheeh Al I’tiqadat, pg 131-132
It is highly probable that ar-Rida (as) was poisoned, yet this cannot be confirmed. As for the others, there is no justification for the claim that they were either poisoned or murdered or killed through persecution, since the reports concerning this matter are extremely confused, and there are no means of proving it definitely.
In a different book, Shaykh al-Mufid writes:
وقُبِض صلى الله عليه وآله بالمدينة مسموماً يوم الاثنين لليلتين بقيتا من صفر سنة عشر من هجرته, وهو ابن ثلاث وستين سنة
And he ﷺ passed in Medina while poisoned, it was on Monday with 2 days left of Safar in the 10th year after Hijrah, and he was 63 yearsAl Muqni’a, pg 456
عن أبي عبد الله عليه السلام قال: تدرون مات النبي صلى الله عليه وآله أو قتل ان الله يقول: ” أفإن مات أو قتل انقلبتم على أعقابكم ” فسم قبل الموت انهما سقتاه [قبل الموت] فقلنا انهما وأبوهما شر من خلق الله
It has been narrated on the authority of Abi Abdullah (as) that he said: “Do you know whether the Prophet ﷺ died a natural death or was murdered? Allah says: “So if he was to die or be killed, would you turn back on your heels [to unbelief]?”. So he was poisoned before he died. They administered him a drink. So we [who were present with the Imam] said that they and their fathers were among the worst of Allah’s creations.”Tafsir Al-‘Ayyashi, vol 1, pg 200
Those who accept this hadith interpret it as referring to Aisha and Hafsa having administered the poison. This narration was mentioned in Tafsir al-’Ayyashi of Muhammad b. Mas’ud al-‘Ayyashi and, in its extant form, which is only a fragment of the original Tafsir al-’Ayyashi, there is no full chain provided for this narration. As such, the narration is graded mursal and therefore weak  and, while the author has been praised and deemed trustworthy, he was not known to rely only on reliable narrators. Rather, Shaykh al-Najashi tells us something about Muhammad b. Mas’ud to the opposite effect:
وكان يروي عن الضعفاء كثيرا
And he used to narrate a lot from the weak [narrators]Rijal al-Najashi, pg 350
قال علي بن إبراهيم كان سبب نزولها ان رسول الله صلى الله عليه وآله كان في بعض بيوت نسائه وكانت مارية القبطية تكون معه تخدمه وكان ذات يوم في بيت حفصة فذهبت حفصة في حاجة لها فتناول رسول الله مارية، فعلمت حفصة بذلك فغضبت وأقبلت على رسول الله صلى الله عليه وآله وقالت يا رسول الله هذا في يومي وفي داري وعلى فراشي فاستحيا رسول الله منها، فقال كفى فقد حرمت مارية على نفسي ولا أطأها بعد هذا ابدا وأنا أفضي إليك سرا فان أنت أخبرت به فعليك لعنة الله والملائكة والناس أجمعين فقالت نعم ما هو؟ فقال إن أبا بكر يلي الخلافة بعدي ثم من بعده أبوك فقالت من أخبرك بهذا قال الله أخبرني فأخبرت حفصة عائشة من يومها ذلك وأخبرت عائشة أبا بكر، فجاء أبو بكر إلى عمر فقال له ان عائشة أخبرتني عن حفصة بشئ ولا أثق بقولها فاسأل أنت حفصة، فجاء عمر إلى حفصة، فقال لها ما هذا الذي أخبرت عنك عائشة، فأنكرت ذلك قالت ما قلت لها من ذلك شيئا، فقال لها عمر إن كان هذا حقا فأخبرينا حتى نتقدم فيه، فقالت نعم قد قال رسول الله ذلك فاجتمع….. على أن يسموا رسول الله
And Ali b. Ibrahim said these verses were revealed when one day the Holy Prophet ﷺ was at Hafsa’s place and Mariya the Copt was in his service. During that time Hafsa went out on some errand and the Prophet had relations with Mariya. When Hafsa came to know about this, she was very angry and she said: O Messenger of Allah ﷺ, you had relations with a slave girl on my bed, and on the day of my turn?” The Prophet was embarrassed at this and he said, “Cool down, I will not have relations with Mariya again. I have made her unlawful for myself.” But he told her that she must keep this matter concealed otherwise the divine curse will be upon her and the anger of the angels and the ridicule of all people. Hafsa said that she will maintain a secret. But what is the secret? The Prophet said: “It is that Abu Bakr will become the Caliph after me through injustice and oppression and after him, your father will become the Caliph.” Hafsa asked him, “Who has told you this?” The Holy Prophet ﷺ said that “the Almighty Allah has informed me about it.” Hafsa revealed it to Ayesha the same day and she mentioned it to her father. Abu Bakr came to Umar and said that “Ayesha has quoted Hafsa thus, but I don’t trust her statement, you ask Hafsa directly if this is true?” Umar came to Hafsa, “Is it true what Ayesha mentioned on your authority?” Initially Hafsa denied having said any such thing to Ayesha. Umar said, “Don’t conceal this from us if it is true, so that we may plan about it beforehand.” Hafsa said, “Yes, the Holy Prophet ﷺ mentioned thus.” Then the two men and their daughters plotted to poison the Prophet.Tafseer al-Qummi, vol 2, pg 367
Tafsir al-Qummi is wrongly attributed to Ali b. Ibrahim. The scholars of rijal and hadith such as Shaykh Mohseni have mentioned this, and the latter also narrates a similar opinion from Sayed al-Sistani:
أقول : من هذا الّذي يقول حدثني؟ وأمّا العبّاس ، فلم أجد ترجمته لحد الآن فهو مجهول.
وقال السّيد السيستاني (طال عمره) ، لي شفاها أن واحدا من تلاميذ علي بن إبراهيم جمع روايات تفسيره وروايات أبي الجارود في كتاب واشتهر هذا الكتاب باسم تفسير علي بن إبراهيم.
I [Shaykh Mohseni] say: Who is the one who says ‘it has been narrated to me’? And if it is Al-Abbas, then I have not found any biography for him till this day, so he is unknown.Buhuth Fi ‘Ilm al-Rijal, pg 430
And Sayed Sistani (ha) told me verbally that [his view is that], one of the students of Ali b. Ibrahim gathered narrations from his tafsir and the narrations from Abi al-Jarud in a book, and it became famous with the name Tafseer Ali b. Ibrahim
We don’t know who compiled this book, nor who is saying “Ali b. Ibrahim said:”, nor is there any chain for this attribution to Ali b. Ibrahim. Additionally, it is not even mentioned that this is heard from the Imam: rather, it just says that the above was said by Ali b. Ibrahim. Therefore, even if one were to assume the correct attribution of the book, the statement would still carry no value for us.
حدثنا ابراهيم بن هاشم عن جعفر بن محمد عن عبد الله بن ميمون القداح عن ابى عبد الله عليه السلام قال سمت اليهودية النبي صلى الله عليه وآله في ذراع قال وكان رسول الله صلى الله عليه وآله يحب الذراع والكتف ويكره الورك لقربها من المبال قال لما اوتى بالشوا اكل من الذراع وكان يحبها فاكل ما شاء الله ثم قال الذراع يا رسول الله صلى الله عليه وآله انى مسموم فتركه وما ذاك ينتقض به سمه حتى مات صلى الله عليه وآله.
It is narrated to us by Ibrahim b. Hashim from Ja’far b. Muhammad from Abdullah b. Maymoon Al-Qaddah that Abu Abdullah عليه السلام said: ‘A Jewess poisoned the Prophet ﷺ in a forearm (of a grilled sheep). And the Messenger of Allah ﷺ used to love the forearm and the shoulder, and disliked the thighs due to its vicinity from the urinary tract’. He then said: ‘When she came with the grill, he ate from the forearm, and he loved it, so he ate whatever Allah so Desired. Then the forearm said, ‘O Messenger of Allah ﷺ, I am poisoned’. So, he left it, and the poison did not cease to infringe with him until he passed away ﷺ’’Basair al-Darajat, pg 523
حدثنا احمد بن محمد عن الحسين بن سعيد عن القاسم بن محمد عن على عن ابى بصير عن ابى عبد الله عليه السلام قال سم رسول الله صلى الله عليه وآله يوم خيبر فتكلم اللحم فقال يارسول الله صلى الله عليه وآله انى مسموم قال فقال النبي صلى الله عليه وآله عند موته اليوم قطعت مطاياى الاكلة التى اكلت بخيبر وما من نبى ولا وصى والا شهيد.
It is narrated to us by Ahmad b. Muhammad from Al-Hussain b. Saeed from Al-Qasim b. Muhammad from Ali from Abi Baseer that Abu Abdullah عليه السلام said: ‘The Messenger of Allah ﷺ was poisoned on the day of Khaybar. The meat spoke and said, ‘O Messenger of Allah ﷺ! I am poisoned’. He [the Imam] said: ‘The Prophet ﷺ said during his passing: ‘My [?] is being cut by the meal which I ate at Khaybar, and there is no Prophet nor a succesor except that he is a martyr’’Basair al-Darajat, pg 523
Both chains here are unreliable due to people of unknown reliability being present in the chains. This in addition to an even bigger problem in the transmission of the book: we cannot ascertain that the Basa’ir al-Darajat we have today is the same one as authored by the companion of Imam Hassan al-Askari (as), Shaykh Saffar al-Qummi (d. 290 AH), because it did not reach us reliably. The version we currently have is rather an amalgamation of several incongruous manuscripts.
وأخبرني جماعة، عن أبي عبد الله محمد بن أحمد الصفواني، قال: حدثني الشيخ الحسين بن روح رضي الله عنه أن يحيى بن خالد سم موسى بن جعفر عليهما السلام في إحدى وعشرين رطبة وبها مات، وأن النبي والائمة عليهم السلام ما ماتوا إلا بالسيف أو السم، وقد ذكر عن الرضا عليه السلام أنه سم، وكذلك ولده وولد ولده.
And a group narrated to me from Abu Abdullah Muhammad b. Ahmad as-Safwani who said: Shaykh al-Husayn b. Ruh (ra) narrated to me that Yahya b. Khalid poisoned Musa b. Ja`far (as) with twenty-one unripe dates, by which he died. And [he also narrated] that the Prophet and the Imams (as) did not die except by the sword or by poison. And he mentioned that al-Ridha (as) was poisoned, as well as his son and his grandson.Al-Ghayba by Shaykh al-Tusi, pg 408-409
While this narration is authentic, it is not narrated from the Imam himself, but from the third deputy of the Qa’im (atfs). This does not mean that the narration is useless; it could still represent an accurate historiography. It is interesting to note, however, that despite the existence of this report, Shaykh al-Mufid remained unconvinced of the Prophet’s ﷺ death by poison.
Worth noting also is that the words of the deputy are not treated the same as the words of an infallible. Sayed al-Sistani says as much regarding the hujjiyah [probative force] of the fatwa of a deputy:
فان قلت: يكفي في الحجية كونه فتوى حسين بن روح رضي اللّه عنه فانه النائب الخاص.
قلت: ليس كذلك وليس هو معصوماً ولا حجية في فتواه وهو الذي اشرف على تأليف كتاب التكليف للشلمغاني وصححه واراد بذلك ان يكون الكتاب الرسمي للشيعة واعترف بصحته علماء بغداد ولم يناقش فيه علماء قم الا في موردين واليه يرجع اكثر الاجماعات المدعاة. ومع ذلك فقد خالفه في عصره بعض العلماء وافتوا برأيهم كالكليني قدس سره
So if you say: The fatwa being from Husayn b. Ruh (ra) himself is sufficient to prove its hujjiyah because he was from the specified deputiesDictated from Sayed al-Sistani by Allamah Murtadha al-Mohri; Kitab al-Salat, pg 125
I say: It is not like that, and he is not infallible, and there is no hujjiyah in his fatwa, and he is the one who endorsed “Kitab al-Takleef”  by al-Shalmaghani and reviewed it with the intention to make it an official religious guide for the Shia, and the scholars of Baghdad attested to its correctness, and the scholars of Qum also did not find any faults with it except on two issues and many of the Imami jurisprudential consensuses have their roots in that book. However, despite that, some of the scholars in that period differed from this book [in their rulings] and issued religious edicts [independent of it], by their own judgement such as Shaykh al-Kulayni (qs)
‘Uyun Akhbar al-Ridha
حَدَّثَنا مُحَمَّد بن مُوسَى بن المُتِوَكِّل رَضِىَ اللهُ عَنْهُ قالَ حَدَّثَنا عَلِيٍّ بن إِبراهِيم بن هاشِمٍ عَن أبِيهِ عَن أبي الصلت عَبد السلام بن صالح الهروي قالَ سَمِعتُ الرِّضا عَلَيْهِ السَّلامُ يَقُولُ: واللَّهِ مَا مِنَّا إِلا مَقْتُولٌ شَهِيدٌ.فَقِيلَ لَهُ فَمَنْ يَقْتُلُكَ يَا ابْنَ رَسُولِ اللَّهِ قَالَ شَرُّ خَلْقِ اللَّهِ فِي زَمَانِي يَقْتُلُنِي بِالسَّمِّ ثُمَّ يَدْفِنُنِي فِي دَارِ مَضِيعَةٍ وَبِلادِ غُرْبَةٍ أَلا فَمَنْ زَارَنِي فِي غُرْبَتِي كَتَبَ اللَّهُ عَزَّ وَجَلَّ لَهُ أَجْرَ مِائَةِ أَلْفِ شَهِيدٍ وَمِائَةِ أَلْفِ صِدِّيقٍ وَمِائَةِ أَلْفِ حَاجٍّ وَمُعْتَمِرٍ وَمِائَةِ أَلْفِ مُجَاهِدٍ وَحُشِرَ فِي زُمْرَتِنَا وَجُعِلَ فِي الدَّرَجَاتِ الْعُلَى مِنَ الْجَنَّةِ رَفِيقَنَا
It was narrated to us by Muhammad ibn Musa ibn al-Mutawakkil (ra) from Ali b. Ibrahim b. Hashem from his father from Abil Salt al-Harawi who said that he had heard Al-Ridha (as) say: “By God! There is none from us but that he will be killed and become a martyr.”‘Uyun Akhbar al-Ridha, vol 2, pg 256
He was asked, “O son of the Messenger of Allah! Who will murder you?”
He replied, “The most wicked creature of God in my time (Al-Ma’mun) will kill me using poison. Then he will bury me in a very tight house in a strange town. Know that whoever visits me in my loneliness, God the Highest will record for him the reward of one-hundred thousand martyrs, one-hundred thousand honest ones, one-hundred thousand obligatory and ‘Umra (supererogatory) pilgrimages, and one-hundred thousands fighters in the way of God. He will also be resurrected among us (the Imams). He will be established in high ranks in Heaven as our friend.”
The only potential problem in this chain is the narrator Shaykh al-Saduq initially takes the narration from, Muhammad ibn Musa ibn al-Mutawakkil, as there is no explicit authentication for him. Sayed al-Khoe’i still considered him reliable , so the chain would be reliable according to him. Shaykh Mohseni also considered the chain reliable but mentioned that the content has problems:
[..] والمعتبرة سنداً من رواياته ما ذكرت برقم 1، على الارجح على اشكال في متنه و برقم 2 على اشكال قوي في متنه أيضاً
And the narrations which have a reliable chain are, #1 with a likely problem in its content, and #2 with a strong objection to its content aswellMashra’at Bihar al-Anwar, vol 2, pg 481
(This problem he is referring to is most likely the latter part of the hadith rather than the statement regarding being martyrs).
If this narration is to be considered reliable it would strengthen what Shaykh Husayn b. Ruh said.
It is important to note that this article did not discuss all the narrations on the subject of the circumstances of the Prophet’s ﷺ death, but only the most popular ones which are used by the Shia. There are also narrations in Sunni hadith books which allude to the Prophet ﷺ being poisoned.
Since none of the narrations regarding the details of his passing seem to have reached us reliably, nor are they mass-transmitted, nor are they in agreement with each other, we choose to adopt the view of Shaykh Mohseni:
و هل النبى صل الله عليه و آله و سلّم مات أو مضى مسموما و مقتولا؟ القرآن ابهمه فى قوله و خطابه لا صحابه صل الله عليه و آله و سلّم (أفان مات أو قتل اتقيلبتم اعقابكم) و تدل بعض الروايات المتقدمة و المذكورة في هذا الباب بارقام 21، 22، 23 على انه صل الله عليه و آله و سلّم مضى مسموما، روحي و ارواح العالمين له الفداء.
So did the Prophet ﷺ die [naturally] or did he pass away poisoned and killed? The Qur’an keeps this obscure as we can see by His saying addressing the Sahaba of the Prophet ﷺ; “So if he was to die or be killed, would you turn back on your heels [to unbelief]?” [3:144], and some of the classical narrations that have been mentioned in this chapter (The 2 narrations from Basair, and the narration of Al-‘Ayyashi) point to his ﷺ passing while poisoned, may my soul and the souls of the worlds be sacrificed for himMashra’at Bihar al-Anwar, vol 1, pg 403