Sahih Muslim Book 4, Hadith Number 1417.

Chapter : Excellence of sitting at the place of worship after the dawn prayer and excellence of the mosque.

Abu Sa’id al-Khudri reported Allah’s Messenger (may peace be upon him) as saying: When there are three persons, one of them should lead them. The one among them most worthy to act as Imam is one who is best versed in the Qur’an.