The Book of Pilgrimage
15/55. Chapter:
Shaving the head is preferrable to cutting the hair, although cutting the hair is permissible
Sahih Muslim
وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " اللَّهُمَّ ارْحَمِ الْمُحَلِّقِينَ " . قَالُوا وَالْمُقَصِّرِينَ يَا رَسُولَ اللَّهِ قَالَ " اللَّهُمَّ ارْحَمِ الْمُحَلِّقِينَ " . قَالُوا وَالْمُقَصِّرِينَ يَا رَسُولَ اللَّهِ قَالَ " وَالْمُقَصِّرِينَ " .
Abdullah b. Umar (Allah be pleased with him) reported Allah's Messenger (ﷺ) as having observed: O Allah, have mercy upon those who get their heads shaved. They (the Companions) said: Messenger of Allah, (what about those) who have got their hair clipped? He said: O Allah, have mercy upon those who have got their heads shaved. They (again) said: Allah's Messenger, (what about those) who have got their hair clipped? Thereupon he said: (O Allah, have mercy upon those) who have got their hair clipped.
Reference : Sahih Muslim 1301bIn-book reference : Book 15, Hadith 349USC-MSA web (English) reference : Book 7, Hadith 2984