Musannaf Ibn Abi Shayba 28:968

Khalid ibn Makhlad narrated to us, he said: Sulayman ibn Bilal narrated to us, from Suhayl, from his father, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Goodness is tied to the forelocks of horses until the Day of Resurrection."