أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَنْبَأَنَا عَبْدُ الرَّزَّاقِ، قَالَ أَنْبَأَنَا مَعْمَرٌ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم رَأَى صَبِيًّا حَلَقَ بَعْضَ رَأْسِهِ وَتَرَكَ بَعْضَ فَنَهَى عَنْ ذَلِكَ وَقَالَ ‏"‏ احْلِقُوهُ كُلَّهُ أَوِ اتْرُكُوهُ كُلَّهُ ‏"‏ ‏.‏

It was narrated from Ibn 'Umar that : The Prophet [SAW] saw a boy, part of whose head had been shaven and part had been left. He forbade that and said: "Shave all of it, or leave all of it." Translation Not Available

Book Ref: Sunan An Nisai Book 48 Hadith 5048
Web Ref:  Sunan An Nisai Vol 6 Book 48 Hadith 5051