Do not bare your thigh, nor look at the thigh of any living person or of the dead. In this there is an indication that he was instructing him concerning his own person; Allah knows best.
Al-Ḥāfiẓ al-Bayhaqī (1) said: Abū ʿAbd Allāh al-Ḥāfiẓ informed us; Muḥammad ibn Yaʿqūb informed us; Yaḥyā ibn Muḥammad ibn Yaḥyā narrated to us; Ḍumrah (2) narrated to us; ʿAbd al-Wāḥid ibn Ziyād narrated to us; Maʿmar narrated to us, from al-Zuhrī, from Saʿīd ibn al-Musayyib, who said:
“ʿAlī said: ‘I washed the Messenger of Allah (Allah bless him and grant him peace). I then looked for what normally appears on the dead, but I saw nothing. He was fragrant, alive and dead alike (Allah bless him and grant him peace).’”
Abū Dāwūd has transmitted it in al-Marāsīl, and so has Ibn Mājah (3) through the chain of Maʿmar.
Al-Bayhaqī added in his wording: Saʿīd ibn al-Musayyib said, “Four undertook his burial (Allah bless him and grant him peace): ʿAlī, al-ʿAbbās, al-Faḍl, and Ṣāliḥ, the freedman of the Messenger of Allah (Allah bless him and grant him peace). They dug for him a lahd-grave and arranged the bricks over him.”
Reports of similar purport have been narrated from a group of the Successors—among them ʿĀmir al-Shaʿbī, Muḥammad ibn Qays, ʿAbd Allāh ibn al-Ḥārith, and others—in various wordings whose full exposition would be lengthy here.
Bayhaqī (4) also said: Abū ʿAmr Kaysān (5) narrated, on the authority of Yazīd ibn Bilāl: I heard ʿAlī say, “The Messenger of Allah (Allah bless him and grant him peace) directed in his will that no one should wash him but I; for whoever beholds my nakedness, his eyes will be blotted out.”
ʿAlī continued: “Al-ʿAbbās and Usāmah would hand me the water from behind a curtain, and I did not take hold of a single limb without feeling as though thirty men were helping me turn it, until I had finished washing him.”
The ḥadīth-master Abū Bakr al-Bazzār has likewise related this report with an isnād in his Musnad (6): Muḥammad ibn ʿAbd al-Raḥīm narrated to us; ʿAbd al-Ṣamad ibn al-Nuʿmān narrated to us; Kaysān Abū ʿAmr narrated to us, from Yazīd ibn Bilāl, who said: ʿAlī said (7), “The Prophet (Allah bless him and grant him peace) charged me that no one should wash him besides myself: ‘For whoever sees my nakedness, his eyes will be obliterated.’” ʿAlī added, “Al-ʿAbbās and Usāmah used to hand me the water from behind the curtain.” I say: This narration is exceedingly uncommon.
Bayhaqī (8) further said: Muḥammad ibn Mūsā ibn al-Faḍl informed us; Abū al-ʿAbbās al-Aṣamm informed us; Usayd ibn ʿĀṣim narrated to us; al-Ḥusayn ibn Ḥafṣ narrated to us, from Sufyān, from ʿAbd al-Malik ibn Jurayj, who said: I heard Muḥammad ibn ʿAlī Abū Jaʿfar say, “The Prophet (Allah bless him and grant him peace) was washed three times with water mixed with lote-leaf; he was washed while wearing a shirt, and the water was drawn from a well known as ‘al-Ghars’ in Qubā’.”