Musannaf Ibn Abi Shaybah 27561 — A man writing to another man

Al-Awza'i reported from a certain shaykh that Sayyiduna Zayd bin Thabit (may Allah be pleased with him) wrote a letter to Sayyiduna Mu'awiyah (may Allah be pleased with him) and began with the name of Sayyiduna Mu'awiyah.