Anas reported that when Allah's Apostle ( صلی اللہ علیہ وسلم ) decided to write to the Kisra (the King of Persia), Caesar (Emperor of Rome), and the Negus (the Emperor of Abyssinia), it was said to him that they would not accept the letter without the seal over it; so Allah's Messenger ( صلی اللہ علیہ وسلم ) got a seal made, the ring of which was made of silver and there was engraved on it:
Muhammad, the Messenger of Allah.