Hadith 538
حَدَّثَنَا وَكِيعٌ، حَدَّثَتْنِي أُمُّ غُرَابٍ، عَنْ بُنَانَةَ، قَالَتْ مَا خَضَبَ عُثْمَانُ قَطُّ.
Umm Ghurab narrated that Bunanah said:
’Uthman never dyed his hair.
Reference : Musnad Ahmad 538
In-book reference : Book 4, Hadith 130