Muwatta Malik #937
Hajj
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
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."
About Muwatta Malik
This hadith is #937 from Muwatta Malik, in the Book of Hajj.