Reference: Fataawa al-Lajnah ad-Daa.imah q1 of no.9696
al-Bid'u wal-Muhdathaat wa maa laa asla lahu p192
Question: What is the ruling regarding sending prayers and salutations upon the Messenger before the adhaan?
Response: Sending prayers and salutations upon the Messenger before the adhaan and, similarly, raising one's voice with it after the adhaan is an innovation in the religion. It is confirmed on the authority of the Prophet ﷺ that he said:
«Whoever introduces anything into this matter of ours (i.e. Islaam) that which is not from it, will have it rejected» [Saheeh al-Bukhaaree/2697 and Saheeh Muslim/1718]
And in another narration:
«Anyone who does an act which is not in agreement with us, then he will have it rejected» [Muslim]
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet ﷺ and his family and his companions.
