(1) باب مَا جَاءَ فِي اتِّخَاذِ الْخَاتَمِ
Narrated Anas bin Malik:
The Messenger of Allah (ﷺ) wanted to write to some persian rulers. He was told that they would not read a letter without a seal in the form of a silver ring on which he engraved "Muhammad the Messenger of Allah." (IT)
Reference (IT): Sunan Abi Dawud 4214 (IT)
In-book reference (IT): Book 36, Hadith 1 (IT)
English translation (IT): Book 35, Hadith 4202 (IT)