Sunan an-Nasa'i, Volume 6, Book 48, Hadith 5059 (DarusSalam) ⓘ
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: Hadith 5056 (Reference) & Book 48, Hadith 17 (In-Book)