Musannaf Ibn Abi Shaybah 27516 — A man who writes: Amma ba'd

Muhammad bin Suqah said: I came to Nu'aym bin Abi Hind, and he took out a scroll and showed it to me. In it was written: "From Abu Ubaydah bin al-Jarrah and Mu'adh bin Jabal to Umar bin al-Khattab. Peace be upon you. Amma ba'd (after praise and salutation)." Then, when Sayyiduna Umar (may Allah be pleased with him) wrote his reply to them both, it read: "From Umar bin al-Khattab to Abu Ubaydah bin al-Jarrah and Mu'adh bin Jabal. Peace be upon you both. Amma ba'd."