Sunan an-Nasa'i, Book 48, Hadith 27 (In-Book)

It was narrated that Wa'il bin Hujr said: "I came to the Prophet [SAW] and I had long hair. He said: 'It is not good,' and I thought he meant me, so I went and cut my hair. He said: 'I did not mean you, but this is better.'"

أَخْبَرَنَا أَحْمَدُ بْنُ حَرْبٍ، قَالَ حَدَّثَنَا قَاسِمٌ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَاصِمِ بْنِ كُلَيْبٍ، عَنْ أَبِيهِ، عَنْ وَائِلِ بْنِ حُجْرٍ، قَالَ أَتَيْتُ النَّبِيَّ صلى الله عليه وسلم وَلِي جُمَّةٌ قَالَ ‏"‏ ذُبَابٌ ‏"‏ ‏.‏ وَظَنَنْتُ أَنَّهُ يَعْنِينِي فَانْطَلَقْتُ فَأَخَذْتُ مِنْ شَعْرِي فَقَالَ ‏"‏ إِنِّي لَمْ أَعْنِكَ وَهَذَا أَحْسَنُ ‏"‏ ‏.‏

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