What are the virtues of sending prayers upon the Prophet (peace be upon him)? And is it legislated to send prayers upon him eleven times after supplication?

Allah has commanded His believing servants to send blessings upon His Prophet Muhammad, peace and blessings be upon him. Many hadiths have been narrated regarding its virtues, among them: that whoever sends blessings upon him once, Allah will send blessings upon him tenfold; that it is a purification for the one who prays; and that Jibreel gave the Prophet glad tidings that whoever sends blessings upon him, Allah will send blessings upon him, and whoever sends salutations upon him, Allah will send salutations upon him.

The best times to send blessings upon him are on Friday and its eve. Sending blessings upon him is obligatory at least once in a lifetime. In addition to being an obedience to Allah's command, it is highly encouraged due to its virtues and goodness. The miser is he who does not send blessings upon him when he is mentioned.

There is no specific number for the supplication after sending blessings upon the Prophet; rather, what is established is to ask for it before supplication and after praising and lauding Allah.