Muwatta Malik #304
Prayer in Congregation
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
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."
About Muwatta Malik
This hadith is #304 from Muwatta Malik, in the Book of Prayer in Congregation.