880. hadíth
وَقَالَ عَلِيٌّ عَلَيْهِ اَلسَّلاَمُ قَالَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: «يَؤُمُّكُمْ أَقْرَؤُكُمْ وَ يُؤَذِّنُ لَكُمْ خِيَارُكُمْ وَ فِي حَدِيثٍ آخَرَ أَفْصَحُكُمْ.
Imam Ali (a.s) said that the Messenger of Allah (saws) said: "The one who leads you in prayer should be the one who has the most knowledge of the Qur'an among you, and the one who calls the adhan (mu'adhdhin) should be the best among you." In another narration, it is said: "the most articulate among you."