Does a Muslim become an infidel if he does not supplicate upon the Prophet (peace be upon him) when he is mentioned, and is it obligatory to supplicate upon him in order, for a number of missed prayers?

A Muslim must invoke blessings upon the Prophet, peace and blessings be upon him, when he is mentioned. Some scholars have gone further, deeming it obligatory, citing the hadiths: "May the nose of a man be rubbed in dust, in whose presence I am mentioned and he does not invoke blessings upon me," and "The miser is he in whose presence I am mentioned and he does not invoke blessings upon me." It is desirable to invoke blessings upon him every time he is mentioned, and increasing these invocations is more beneficial, for "The closest of people to me on the Day of Resurrection will be those who invoke the most blessings upon me." The majority of scholars view it as desirable, not obligatory, and therefore there is no make-up required for someone who missed it. In the event of feeling disbelief, one must repent, seek forgiveness, return to Allah, and pronounce the Two Testimonies of Faith.