INTERVAL BETWEEN THE CALL TO PRAYER BY BILAL AND THE CALL OF THE SON OF UMM MAKTUM H 1257 "The Messenger of Allah, praise and peace be upon him, appointed two callers for the prayer; Bilal and the son of Umm Maktum. The Prophet, praise and peace be upon him, said, 'Bilal calls the (warning) Adhan while it is still night. So continue eating until ibn Umm Maktum calls it (the prayer).' There was only a brief interval between the two." R 1257 Bukhari and Muslim with a chain up to ibn Omar who related that the Messenger of Allah, praise and peace be upon him, said this.
1231- وعن ابن عمر رضي الله عنهما ، قَالَ : كَانَ لرسولِ الله صلى الله عليه وآله وسلم مُؤَذِّنَانِ : بِلاَلٌ وَابْنُ أُمِّ مَكْتُومٍ ، فَقَالَ رسول الله صلى الله عليه وآله وسلم : "إنْ بِلالاً يُؤَذِّنُ بِلَيْلٍ ، فَكُلُوا وَاشْرَبُوا حَتَّى يُؤَذِّنَ ابْنُ أُمِّ مَكْتُومٍ" قَالَ : وَلَمْ يَكُنْ بَيْنَهُمَا إِلاَّ أنْ يَنْزِلَ هَذَا وَيَرْقَى هَذَا . متفقٌ عَلَيْهِ .