English Translation
Narrated Anas bin Malik: When the Prophet intended to write to the Byzantines, the people said, "They do not read a letter unless it is sealed (stamped)." Therefore the Prophet took a silver ring----as if I am looking at its glitter now----and its engraving was: 'Muhammad, Apostle of Allah'
This hadith is from Sahih al-Bukhari, the most rigorously authenticated collection in Islamic scholarship. No editorial opinion is added.