وَعَنْ أَنَسٍ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَرَادَ أَنْ يَكْتُبَ إِلَى كِسْرَى وَقَيْصَرَ وَالنَّجَاشِيِّ فَقِيلَ: إِنَّهُمْ لَا يَقْبَلُونَ كِتَابًا إِلَّا بِخَاتَمٍ فَصَاغَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ خَاتَمًا حَلْقَةَ فِضَّةٍ نُقِشَ فِيهِ: مُحَمَّدٌ رَسُولُ اللَّهِ. رَوَاهُ مُسْلِمٌ. وَفِي رِوَايَةٍ لِلْبُخَارِيِّ: كَانَ نَقْشُ الْخَاتَمِ ثَلَاثَةَ أَسْطُرٍ: مُحَمَّدٌ سَطْرٌ ورسولُ الله سطر وَالله سطر

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.