الكافي 1/4/111/39

39. Certain persons of our people have narrated from in a in a marfu‘ manner have narrated from Muhammad b. Sinan from Dawud b. Kathir al-Raqqi who has said that he asked Abu ‘Abdallah عليه السلام the following: “What is the meaning of ‘peace be with the Messenger of Allah?’” The Imam عليه السلام said: “When Allah, the Most Holy, the Most High, created His Prophet, the executor of the will of His Prophet, the daughter of His Prophet, their two sons, all the Imams عليه السلام and their Shi‘a (followers), He made them to form a covenant to exercise patience, help to exercise patience, establish good relations and live piously before Allah. He promised to give to them the blessed land and sacred sanctuary and to bring down to them the constructed house (al-Bayt al-Ma‘mur) and to manifest to the raised ceiling (Al Saqf al-Marfu‘) and grant them relief against their enemies. Also Allah grants them the earth that He will change with peace and protect all that is therein for them without any quarrels therein against the enemies and there will exist all that they love. The Messenger of Allah made a similar covenant with all the Imams and their Shi‘a. “Offering of peace to him is a mention of that covenant and renewing it before Allah, so that pehaps He, the Most Majestic, the Most gracious, would allow that peace to take place soon for all of you with all that is therein.”