The Prophet ﷺ as saying: Jews and Christians do not dye (their beards), so act differently from them.  

النَّبِيَّ ﷺ قَالَ إِنَّ الْيَهُودَ وَالنَّصَارَى لاَ يَصْبُغُونَ فَخَالِفُوهُمْ  

Abu Quhafah was brought on the day of the conquest of Mecca with head and beard while like hyssop. The Messenger of Allah ﷺ said: Change this something, but avoid black.  

أُتِيَ بِأَبِي قُحَافَةَ يَوْمَ فَتْحِ مَكَّةَ وَرَأْسُهُ وَلِحْيَتُهُ كَالثَّغَامَةِ بَيَاضًا فَقَالَ رَسُولُ اللَّهِ ﷺ غَيِّرُوا هَذَا بِشَىْءٍ وَاجْتَنِبُوا السَّوَادَ  

The Prophet ﷺ said: The best things with which grey hair are changed are henna and katam.  

قَالَ رَسُولُ اللَّهِ ﷺ إِنَّ أَحْسَنَ مَا غُيِّرَ بِهِ هَذَا الشَّيْبُ الْحِنَّاءُ وَالْكَتَمُ  

I went with my father to the Prophet ﷺ. He had locks hanging down as far as the lobes of the ears stained with henna, and he was wearing two green garments.  

انْطَلَقْتُ مَعَ أَبِي نَحْوَ النَّبِيِّ ﷺ فَإِذَا هُوَ ذُو وَفْرَةٍ بِهَا رَدْعُ حِنَّاءَ وَعَلَيْهِ بُرْدَانِ أَخْضَرَانِ  

My father said to him (the Prophet): Show me what is on your back, for I am a physician. He (the Prophet) said: You are only a soother. Its physician is He Who has created it.  

لَهُ أَبِي أَرِنِي هَذَا الَّذِي بِظَهْرِكَ فَإِنِّي رَجُلٌ طَبِيبٌ قَالَ اللَّهُ الطَّبِيبُ بَلْ أَنْتَ رَجُلٌ رَفِيقٌ طَبِيبُهَا الَّذِي خَلَقَهَا  

I and my father came to the Prophet ﷺ. He said to a man or to my father: Who is this? He replied: He is my son. He said: Do not commit a crime on him. He had stained his beard with henna.  

أَتَيْتُ النَّبِيَّ ﷺ أَنَا وَأَبِي فَقَالَ لِرَجُلٍ أَوْ لأَبِيهِ مَنْ هَذَا قَالَ ابْنِي قَالَ لاَ تَجْنِي عَلَيْهِ وَكَانَ قَدْ لَطَخَ لِحْيَتَهُ بِالْحِنَّاءِ  

He did not dye his hair, but Abu Bakr and 'Umar dyed their hair.  

عَنْ خِضَابِ النَّبِيِّ ﷺ فَذَكَرَ أَنَّهُ لَمْ يَخْضِبْ وَلَكِنْ قَدْ خَضَبَ أَبُو بَكْرٍ وَعُمَرُ ؓ