The Book of Adornment
48/56. Chapter:
Trimming the Mustache and Letting the Beard Grow
Sunan an-Nasai
أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، قَالَ أَخْبَرَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " أَحْفُوا الشَّوَارِبَ وَأَعْفُوا اللِّحَى " .
It was narrated from Ibn 'Umar that: The Prophet [SAW] said: "Trim the mustache and let the beard grow."
Reference : Sunan an-Nasa'i 5226In-book reference : Book 48, Hadith 187English translation : Vol. 6, Book 48, Hadith 5228