Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Ja'far bin Burqan that he says Hazrat Umar bin Abdul Aziz, may Allah have mercy on him, wrote a letter: "Amma ba'd! Indeed, some people seek the world through deeds of the Hereafter, and some storytellers have innovated the practice of sending blessings upon their caliphs and rulers in the manner of the Noble Prophet, peace and blessings be upon him. So when this letter of mine reaches you, command the people that they should send blessings upon the Noble Prophet, peace and blessings be upon him, and the other prophets. And supplicate for the general Muslim people, and leave out others besides them."