Language:
كتاب الحج
25  
Hajj (Pilgrimage)
(127)
Chapter: To shave the head and to have the head-hair cut short on finishing the Ihram
(127)
باب الْحَلْقِ وَالتَّقْصِيرِ عِنْدَ الإِحْلاَلِ
Sahih al-Bukhari 1728

Narrated Abu Huraira:

Allah's Messenger (ﷺ) said, "O Allah! Forgive those who get their heads shaved." The people asked. "Also those who get their hair cut short?" The Prophet (ﷺ) said, "O Allah! Forgive those who have their heads shaved." The people said, "Also those who get their hair cut short?" The Prophet (invoke Allah for those who have their heads shaved and) at the third time said, "also (forgive) those who get their hair cut short."

حَدَّثَنَا عَيَّاشُ بْنُ الْوَلِيدِ، حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، حَدَّثَنَا عُمَارَةُ بْنُ الْقَعْقَاعِ، عَنْ أَبِي زُرْعَةَ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ اللَّهُمَّ اغْفِرْ لِلْمُحَلِّقِينَ ‏"‏‏.‏ قَالُوا وَلِلْمُقَصِّرِينَ‏.‏ قَالَ ‏"‏ اللَّهُمَّ اغْفِرْ لِلْمُحَلِّقِينَ ‏"‏‏.‏ قَالُوا وَلِلْمُقَصِّرِينَ‏.‏ قَالَهَا ثَلاَثًا‏.‏ قَالَ ‏"‏ وَلِلْمُقَصِّرِينَ ‏"‏‏.‏
Reference : Sahih al-Bukhari 1728
In-book reference : Book 25, Hadith 206
USC-MSA web (English) reference : Vol. 2, Book 26, Hadith 786
  (deprecated numbering scheme)