What is the source of the expressions "peace and blessings be upon him," "peace be upon him," and "may Allah be pleased with him" in bestowing reverence upon prophets and companions?

Indeed, it is Allah who favored the prophets and messengers, chose them, elevated some of them in rank, honored the Companions, and was pleased with them. This is as stated in His exalted words: "Allah chooses messengers from the angels and from the people," and His words: "Those messengers—We preferred some of them over others," and His words concerning the Companions: "Allah was pleased with them, and they with Him." Therefore, prayers and salutations are invoked upon the prophets and messengers, and Allah's pleasure is sought for the Companions. It is permissible to invoke prayers upon those other than the prophets, provided that it is not taken as a regular slogan.