Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.107B.

Section : To say aloud “Peace and blessings upon the Messenger” after the azhan.

This is a hated innovation. Ibn Hajr says in al-Fatawa al-Kubra, “Our shaikhs and others have given a legal verdict about the prayers and salutations for the Prophet after the azhan and how the callers to prayer do it. Their verdict is that (the prayers for the Prophet) has its root in the sunnah, but the manner in which they perform it is an innovation.” Muhammad ‘Abduh was asked about saying the prayers and salutation for the Prophet subsequent to the azhan and he said, “The azhan, as mentioned in al-Khaniyyah, is only for the prescribed prayers. It consists of fifteen phrases, the last being La ilaha illal-lah. Whatever is mentioned before or after it is an innovation. It has been introduced for rhythm, and nothing else. There is hardly a scholar who has allowed it, nor does it make any sense to say that it is a good innovation, for every innovation in matters of worship is evil. Whoever claims that it is not for melody is lying.”