عَنِ ابْنِ عُمَرَ، قَالَ: كَانَ لِرَسُولِ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ مُؤَذِّنَانِ بِلَالٌ، وَابْنُ أُمِّ مَكْتُومٍ الْأَعْمَى(مسلم : ۳۸۰)
Translation
Hazrat Ibn Umar (may Allah be pleased with them both) narrated, he said: The Messenger of Allah (PBUH) had two Mu'adhins, Bilal and the blind Ibn Umm Maktum (may Allah be pleased with them both).