Musnad Abu Ya'la al-Mawsili 155:117

Zuhayr narrated to us, Sufyan ibn 'Uyaynah narrated to us, from al-Zuhri, from Abu Salamah and Sulayman ibn Yasar, from Abu Hurayrah, attributing it to the Prophet (may Allah bless him and grant him peace), who said: "Indeed, the Jews and the Christians do not dye [their hair], so differ from them."