Musannaf Ibn Abi Shayba 16:773

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from al-A'mash, from Thabit ibn 'Ubayd, from Abu Ja'far al-Ansari, he said: I saw Abu Bakr, and his head and his beard were as if they were the embers of the Ghadha tree.