Musannaf Ibn Abi Shayba 27:151

Zayd ibn al-Hubab narrated to us, from Musa ibn Ubaydah, who said: Qays ibn Abd al-Rahman ibn Abi Sa'sa'ah narrated to me, from Sa'd ibn Ibrahim, from his father, from his grandfather, from Abd al-Rahman ibn Awf, that the Prophet, peace and blessings of Allah be upon him, said: "I prostrated in gratitude for what He has tested me with regarding my nation: whoever from my nation sends one prayer upon me, ten good deeds are written for him, and ten evil deeds are removed from him."