Sahih Bukhari Volume 1, Book 10, Hadith 617

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ إِنَّ بِلاَلاً يُؤَذِّنُ بِلَيْلٍ، فَكُلُوا وَاشْرَبُوا حَتَّى يُنَادِيَ ابْنُ أُمِّ مَكْتُومٍ ‏"‏‏.‏ ثُمَّ قَالَ وَكَانَ رَجُلاً أَعْمَى لاَ يُنَادِي حَتَّى يُقَالَ لَهُ أَصْبَحْتَ أَصْبَحْتَ‏

Narrated By Salim bin Abdullah : My father said that Allah s Apostle said, "Bilal pronounces 'Adhan at night, so keep on eating and drinking (Suhur) till Ibn Um Maktum pronounces Adhan." Salim added, "He was a blind man who would not pronounce the Adhan unless he was told that the day had dawned."