Musannaf Ibn Abi Shaybah 35793 — A man writing to the People

Abu Burdah said: The Prophet (peace and blessings be upon him) wrote a letter to a man from the People of the Book and wrote: 'Aslim anta' (Embrace Islam). The Prophet (peace and blessings be upon him) had not yet finished writing the letter when a letter arrived from that same man. It was read out, and it contained a greeting of peace. So the Prophet (peace and blessings be upon him) also returned the greeting of peace at the end of his letter.