This chain is authentic according to the standards of the two Shaykhs.
Benefit: The man who was wearing the lower garment was ʿAmr ibn Zurārah, as mentioned in a report of al-Ṭabarānī from Abū Umāmah. Al-Ṭabarānī related it through several chains, one of which—according to al-Majmaʿ—consists entirely of trustworthy narrators.
Aḥmad likewise transmitted the hadith from this same ʿAmr, though he named him ʿAmr ibn Fulān al-Anṣārī. The chain there is sound: its transmitters are the men of the Six books except for al-Walīd ibn Sulaymān, who is reliable, as stated in al-Taqrīb. Al-Haythamī comments, “Its narrators are trustworthy.”
There is also a narration on this topic from ʿAlī ibn Abī Ṭālib, in which Hamzah (may Allah be pleased with him) raised his gaze to the Prophet’s knees and then up to his navel; the full text will appear shortly, God willing.
From these aḥādīth it is clear that the knee is not part of the ʿawrah, for two reasons:
- The Messenger of Allah uncovered it without any necessity.
Al-Shawkānī’s objection—that the hadith cannot be used to prove the knee is not ʿawrah because the uncovering was prompted by entering the water, and because ʿUthmān’s covering it suggests it is ʿawrah, even though another explanation for his covering is possible and thus the matter remains only conjectural—is therefore dismissed.