The Book of the Adhan (The Call to Prayer)
7/13. Chapter:
What Should The Mu'adhdhin Do While Calling The Adhan?
Sunan an-Nasai
أَخْبَرَنَا مَحْمُودُ بْنُ غَيْلاَنَ، قَالَ حَدَّثَنَا وَكِيعٌ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَوْنِ بْنِ أَبِي جُحَيْفَةَ، عَنْ أَبِيهِ، قَالَ أَتَيْتُ النَّبِيَّ صلى الله عليه وسلم فَخَرَجَ بِلاَلٌ فَأَذَّنَ فَجَعَلَ يَقُولُ فِي أَذَانِهِ هَكَذَا يَنْحَرِفُ يَمِينًا وَشِمَالاً .
It was narrated from 'Awn bin Abi Juhaifah that his father said: "I came to the Prophet (S.A.W) and Bilal came out and called the Adhan and he started doing like this in his Adhan, turning to his right and left."
Reference : Sunan an-Nasa'i 643In-book reference : Book 7, Hadith 18English translation : Vol. 1, Book 7, Hadith 644