He was asked about the hair-dye of the Prophet ﷺ and mentioned that he did not dye his hair, but Abu Bakr and Umar did dye theirs.
حدثنا محمد بن عبيد حدثنا حماد عن ثابت
أنه سئل عن خضاب النبي ﷺ فذكر أنه لم يخضب ولكن قد خضب أبو بكر وعمر رضي الله عنهما
Bukhari narrated it in "Clothing," chapter "What Is Mentioned Concerning Gray Hair," hadith no. 5895, and Muslim narrated it in "Virtues," chapter "His Gray Hair," hadith no. 2341/103, both from the hadith of Hammad bin Zayd, through this same chain.