Sunan an-Nasa'i, Hadith 5084 ⓘ
It was narrated that Abu Rimthah said: "I came to the Prophet [SAW] and I saw that he had dyed his beard with yellow dye."
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ إِيَادِ بْنِ لَقِيطٍ، عَنْ أَبِي رِمْثَةَ، رَضِيَ اللَّهُ عَنْهُ قَالَ أَتَيْتُ النَّبِيَّ صلى الله عليه وسلم وَرَأَيْتُهُ قَدْ لَطَخَ لِحْيَتَهُ بِالصُّفْرَةِ .
also referenced under: Book 48, Hadith 45 (In-Book) & Volume 6, Book 48, Hadith 5087 (DarusSalam)