Sahih Bukhari Volume 2, Book 25, Hadith 1728

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما ـ 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 ‏"‏‏.‏ وَقَالَ اللَّيْثُ حَدَّثَنِي نَافِعٌ ‏"‏ رَحِمَ اللَّهُ الْمُحَلِّقِينَ ‏"‏ مَرَّةً أَوْ مَرَّتَيْنِ‏.‏ قَالَ وَقَالَ عُبَيْدُ اللَّهِ حَدَّثَنِي نَافِعٌ وَقَالَ فِي الرَّابِعَةِ ‏"‏ وَالْمُقَصِّرِينَ ‏"‏‏

Narrated By Abdullah bin Umar : Allah's Apostle said, "O Allah! Be merciful to those who have their head shaved." The people said, "O Allah's Apostle! And (invoke Allah for) those who get their hair cut short." The Prophet said, "O Allah! Be merciful to those who have their head shaved." The people said, "O Allah's Apostle! And those who get their hair cut short." The Prophet said (the third time), "And to those who get their hair cut short." Nafi' said that the Prophet had said once or twice, "O Allah! Be merciful to those who get their head shaved," and on the fourth time he added, "And to those who have their hair cut short."