Sunan an-Nasa'i, Hadith 5056 ⓘ
It was narrated from Al-Hasan that: The Prophet [SAW] forbade coming one's hair except every other day.
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا أَبُو دَاوُدَ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم نَهَى عَنِ التَّرَجُّلِ إِلاَّ غِبًّا .
also referenced under: Book 48, Hadith 17 (In-Book) & Volume 6, Book 48, Hadith 5059 (DarusSalam)