Silsilat al-Ahadith al-Sahihah

Umm al-Mu’minin Sayyidah Aisha (may Allah be pleased with her) says that the Messenger of Allah (peace and blessings of Allah be upon him) was sitting with his thigh uncovered. Sayyiduna Abu Bakr (may Allah be pleased with him) sought permission to enter, and he allowed him in while he was in that state. Then Sayyiduna Umar (may Allah be pleased with him) sought permission, and he allowed him in while he was in that state. When Sayyiduna Uthman (may Allah be pleased with him) sought permission, he let his garment down (covering his thigh). When all these people had left, I asked: O Messenger of Allah! Abu Bakr (may Allah be pleased with him) sought permission from you and you remained in that state... (but when Uthman [may Allah be pleased with him] wanted to enter, you covered yourself in this way)? He (peace and blessings of Allah be upon him) said: “Aisha! Should I not show modesty before a man, by Allah, even the angels are modest before him?”