Is it obligatory to send prayers and blessings upon the Messenger of Allah (peace and blessings be upon him)?

Question : Regarding sending prayers upon the Messenger, is it obligatory in one state but not another, or rather, how was it established? Is it obligatory for people to

Answer : No, it is not obligatory for them to send prayers upon him [in general], but it is obligatory when his name is mentioned. This is because it was reported from him (peace and blessings be upon him) that he said, "Ameen," when Jibril said, "May the nose of the man who is mentioned in his presence and does not send prayers upon you be ground in the dust." I said, "Say Ameen," so I said, "Ameen." It is known that the supplication against him that Allah may grind his nose indicates that sending prayers upon him when he is mentioned is obligatory. It has also passed us that it is a pillar of the prayer according to the well-known view of the school of Imam Ahmad, making it obligatory. The important point is that it is obligatory in certain circumstances.