مُوَطَّأُ مَالِكٍ
Muwatta Malik 305
Prayer in Congregation
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ رَجُلاً، كَانَ يَؤُمُّ النَّاسَ بِالْعَقِيقِ فَأَرْسَلَ إِلَيْهِ عُمَرُ بْنُ عَبْدِ الْعَزِيزِ فَنَهَاهُ . قَالَ مَالِكٌ وَإِنَّمَا نَهَاهُ لأَنَّهُ كَانَ لاَ يُعْرَفُ أَبُوهُ .
Yahya related to me from Malik from Yahya ibn Said that a man used to lead the people in prayer in al-Aqiq (a place near Madina), and Umar ibn Abd al-Aziz sent a message to him forbidding him to do so. Malik said, "He only forbade him because his father was not known."
Arabic/English book reference: Book 8, Hadith 16