Sunan Abi Dawud, Hadith 1974

Narrated 'Abd Allah b. 'Umar: That the Messenger of Allah said: O Allah, have mercy on those who have themselves shaved. The people said: Messenger of Allah, and those who have clipped their hair. He again said: O Allah, have mercy on those who have themselves shaved. The people said: Messenger of Allah, those who have clipped their hair. He said: and those who clip their hair.

حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ اللَّهُمَّ ارْحَمِ الْمُحَلِّقِينَ ‏"‏ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ وَالْمُقَصِّرِينَ ‏.‏ قَالَ ‏"‏ اللَّهُمَّ ارْحَمِ الْمُحَلِّقِينَ ‏"‏ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ وَالْمُقَصِّرِينَ ‏.‏ قَالَ ‏"‏ وَالْمُقَصِّرِينَ ‏"‏ ‏.‏

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also referenced under: Hadith 1979 (DarusSalam)