حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِذَا كَانُوا ثَلاَثَةً فَلْيَؤُمَّهُمْ أَحَدُهُمْ وَأَحَقُّهُمْ بِالإِمَامَةِ أَقْرَؤُهُمْ ‏"‏ ‏.‏

Abu Sa'id al-Khudri reported Allah's Messenger (PBUH) 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. Translation Not Available

Book Ref: Sahih Muslim Book 5 Hadith 1417
Web Ref:  Sahih Muslim Book 4 Hadith 672 a