Ibn Umar used to dye his beard with yellow colour so much so that his clothes were filled (dyed) with yellowness. He was asked: Why do you dye with yellow colour? He replied: I saw the Messenger of Allah ﷺ dyeing with yellow colour, and nothing was dearer to him than it. He would dye all his clothes with it, even his turban.
إِنِّي رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَصْبُغُ بِهَا وَلَمْ يَكُنْ شَىْءٌ أَحَبَّ إِلَيْهِ مِنْهَا وَقَدْ كَانَ يَصْبُغُ بِهَا ثِيَابَهُ كُلَّهَا حَتَّى عِمَامَتَهُ
"I saw Ibn 'Umar dyeing his beard yellow with Khaluq and I said: 'O Abu 'Abdur-Rahman, are you dyeing your beard yellow with Khaluq?' He said: 'I saw the Messenger of Allah [SAW] dyeing his beard yellow with it, and there was no other kind of dye that was dearer to him than this. He used to dye all of his clothes with it, even his 'Imamah (turban).'"
إِنِّي رَأَيْتُ رَسُولَ اللَّهِ ﷺ يُصَفِّرُ بِهَا لِحْيَتَهُ وَلَمْ يَكُنْ شَىْءٌ مِنَ الصِّبْغِ أَحَبَّ إِلَيْهِ مِنْهَا وَلَقَدْ كَانَ يَصْبُغُ بِهَا ثِيَابَهُ كُلَّهَا حَتَّى عِمَامَتَهُ قَالَ أَبُو عَبْدِ الرَّحْمَنِ وَهَذَا أَوْلَى بِالصَّوَابِ مِنْ حَدِيثِ قُتَيْبَةَ