Mishkat al-Masabih 22 Clothing كتاب اللباس 142

وَعَنِ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَلْبَسُ النِّعَالَ السِّبْتِيَّةَ وَيَصْفِرُّ لِحْيَتَهُ بِالْوَرْسِ وَالزَّعْفَرَانِ وَكَانَ ابْنُ عُمَرَ يَفْعَلُ ذَلِك. رَوَاهُ النَّسَائِيّ

Ibn ‘Umar said the Prophet used to wear tanned leather sandals and dye his beard yellow with wars (a plant of yellow colour in the Yemen, like sesame) and saffron. And Ibn ‘Umar used to do that. Nasa’i transmitted it.