Mishkat al-Masabih #4203

Anas said that when the Prophet wanted to write to the Persian Emperor, the Byzantine Emperor and the Negus he was told that they would not accept a letter without a seal; so God’s messenger fashioned a seal in the form of a silver ring on which he engraved “Muhammad God’s messenger.” Muslim transmitted it. A version by Bukhari says the engraving on the seal was in three lines, “Muhammad” being one, “messenger” another, and “of God” another.