Musnad Ahmad Hadith 20685

Amr bin Salamah says that when Makkah Mukarramah was conquered, people began to come to the Prophet (peace be upon him). On their return, they would pass by us. My father also went to the Prophet (peace be upon him) with the message of his tribe's acceptance of Islam. When he was about to return, the Prophet (peace be upon him) said, "Appoint as your imam the one who has memorized the most Qur'an." The people considered this, and they did not find anyone who had memorized more Qur'an than me. So, despite my young age, they made me the imam, and I began to lead them in prayer. I used to have a single sheet on my body, and when I would bow or prostrate, it would become short and my private parts would become exposed. Seeing this, an old woman said to the people, "Cover your imam's private parts." So the people made a shirt for me, and I was very happy to receive it.