Hadith Q401
إِذَا كَانَ لِلْمَسْجِدِ مُؤَذِّنَانِ لَا مُؤَذِّنٌ وَاحِدٌ، فَيُؤَذِّنُ أَحَدُهُمَا قَبْلَ طُلُوعِ الْفَجْرِ، وَالْآخَرُ بَعْدَ طُلُوعِهِ بِذِكْرِ خَبَرٍ مُجْمَلٍ غَيْرِ مُفَسَّرٍ.
When there are two muezzins in the mosque instead of one, and one of them gives the call to prayer before the break of dawn and the other gives the call to prayer after the break of dawn, in this regard, the mentioned narration is concise and unexplained.
Hadith 401
Hazrat Salim (may Allah have mercy on him) narrates from his father Sayyiduna Abdullah (may Allah be pleased with him) that the Prophet Muhammad (peace and blessings be upon him) said: "Bilal (may Allah be pleased with him) gives the call to prayer at night, so eat and drink (for keeping the fast) until you hear the call to prayer of Ibn Umm Maktum." Imam Abu Bakr (may Allah have mercy on him) has also narrated from his teacher Makhzumi; in this chain, at every place, the narration is from « عن ».