Musnad Ahmad 32:1051

Bahz narrated to us, Hammam narrated to us, from Qatadah, who said: I asked Anas ibn Malik: "Did the Messenger of Allah (peace and blessings of Allah be upon him) dye his hair?" He said: "It did not reach that point; it was only a little bit at his temples." But Abu Bakr dyed his hair with henna and katam.