He was asked about some people who had discussed invoking blessings upon the Prophet, may Allah bless him and grant him peace. Some said, “It is obligatory at all times, and whoever does not invoke blessings upon him sins.” Others said, “It is obligatory in the prescribed prayers because it is one of their obligatory components. Outside those prayers, it is not obligatory, but whoever invokes blessings upon him is promised a tenfold reward each time.”

He answered:

All praise is due to Allah. The position of al-Shāfi'ī and of Ahmad, according to one of the two opinions reported from him, is that invoking blessings upon the Prophet is obligatory during prayer but not outside it. The position of Abū Hanīfah, Mālik, and Ahmad, according to the other reported opinion, is that it is not obligatory during prayer. Among those who hold this latter view, some say that it is obligatory once in a lifetime, while others say that it is obligatory in any gathering in which he is mentioned. This issue is discussed at length elsewhere. And Allah knows best.