The Book of Prayers
4/7. Chapter:
It Is Recommended For The One Who Hears The Mu'adhdhin To Repeat His Words, Then To Send Salat Upon The Prophet (saws) And Ask Allah To Grant Him Al-Wasilah
Sahih Muslim
حَدَّثَنِي يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ عَطَاءِ بْنِ يَزِيدَ اللَّيْثِيِّ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا سَمِعْتُمُ النِّدَاءَ فَقُولُوا مِثْلَ مَا يَقُولُ الْمُؤَذِّنُ " .
Abu Sa'id al-Khudri reported: When you hear the call (to prayer), repeat what the Mu'adhdhin pronounces.
Reference : Sahih Muslim 383In-book reference : Book 4, Hadith 12USC-MSA web (English) reference : Book 4, Hadith 746