ENOfficial
Umm Ghurab narrated that Bunanah said: ’Uthman never dyed his hair.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا وَكِيعٌ، حَدَّثَتْنِي أُمُّ غُرَابٍ، عَنْ بُنَانَةَ، قَالَتْ مَا خَضَبَ عُثْمَانُ قَطُّ.
sunnah.com
Musnad Ahmad
Book 4Hadith Number 538