Sunan an-Nasa'i, Book 10, Hadith 6 (In-Book) ⓘ
It was narrated from Abu Sa'eed that the Prophet said: "when there are three people let one of them lead the prayer, and the one who is most entitled to lead the prayer is the one who has most knowledge of the Qur'an."
أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، عَنْ يَحْيَى، عَنْ هِشَامٍ، قَالَ حَدَّثَنَا قَتَادَةُ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِذَا كَانُوا ثَلاَثَةً فَلْيَؤُمَّهُمْ أَحَدُهُمْ وَأَحَقُّهُمْ بِالإِمَامَةِ أَقْرَؤُهُمْ " .
also referenced under: Hadith 782 (Reference) & Volume 1, Book 10, Hadith 783 (DarusSalam)