Musnad Ahmad 626:50

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Mansur, who said: I heard al-Musayyib ibn Rafi' narrating from Warrad, the scribe of al-Mughirah ibn Shu'bah, that al-Mughirah wrote to Mu'awiyah: That the Messenger of Allah, peace and blessings of Allah be upon him, used to say when he finished the prayer: "There is no god but Allah alone, He has no partner. To Him belongs the dominion, and to Him belongs the praise, and He is capable of all things. O Allah, there is no preventer of what You have given, and no giver of what You have prevented, and the wealth of the wealthy will not benefit him against You."