Musnad Abu Ya'la al-Mawsili 111:29

Muhammad ibn Jami' narrated to us, Yazid ibn Zuray' narrated to us, Rawh ibn al-Qasim narrated to us, from Suhayl ibn Abi Salih, from his father, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Good is tied to the forelocks of horses."