Mukhtasar Bukhari

‘Sayyiduna Anas bin Malik (may Allah be pleased with him) says that’ when the Prophet Muhammad (peace and blessings of Allah be upon him) intended to write or wrote a letter (to the king of Rome or Persia), it was said to him that those people do not read a letter without a seal (i.e., they do not give it importance). So the Prophet (peace and blessings of Allah be upon him) had a silver ring made, on which “Muhammad Rasul Allah” was engraved. (Sayyiduna Anas, may Allah be pleased with him, says: It feels as if) I am (even now) looking at the whiteness of it in the blessed hand of the Prophet (peace and blessings of Allah be upon him).