Sunan Abi Dawud, Hadith 4207

The tradition mentioned above has also been transmitted by Ibn 'Umar through a different chain of narrators from the Prophet. This version adds: He engraved on it "Muhammad, the Messenger of Allah." and said: "No one must engrave anything in the manner of this signet-ring of mine. He then transmitted the rest of the tradition.

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ أَيُّوبَ بْنِ مُوسَى، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، فِي هَذَا الْخَبَرِ عَنِ النَّبِيِّ صلى الله عليه وسلم فَنَقَشَ فِيهِ ‏"‏ مُحَمَّدٌ رَسُولُ اللَّهِ ‏"‏ ‏.‏ وَقَالَ ‏"‏ لاَ يَنْقُشْ أَحَدٌ عَلَى نَقْشِ خَاتَمِي هَذَا ‏"‏ ‏.‏ ثُمَّ سَاقَ الْحَدِيثَ ‏.‏

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also referenced under: Hadith 4219 (DarusSalam)