Sunan an-Nasa'i, Hadith 5083 ⓘ
It was narrated that Abu Rimthah said: "My father and I came to the Prophet [SAW] and he had dyed his beard with Henna."
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ إِيَادِ بْنِ لَقِيطٍ، عَنْ أَبِي رِمْثَةَ، قَالَ أَتَيْتُ أَنَا وَأَبِي النَّبِيَّ، صلى الله عليه وسلم وَكَانَ قَدْ لَطَخَ لِحْيَتَهُ بِالْحِنَّاءِ .
also referenced under: Book 48, Hadith 44 (In-Book) & Volume 6, Book 48, Hadith 5086 (DarusSalam)