Muwatta Malik:Hajj:Hadith 937
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ مَنْ ضَفَرَ رَأْسَهُ فَلْيَحْلِقْ وَلاَ تَشَبَّهُوا بِالتَّلْبِيدِ ‏.‏

Yahya related to me from Malik from Nafi from ‘Abdullah ibn ‘Umar that Umar ibn al-Khattab said, “Someone who puts plaits in his hair should shave his head, and do not plait your hair in such a way that it seems you have matted it.”