Jami` at-Tirmidhi 1636

Narrated Abu Hurairah: That the Messenger of Allah (ﷺ) said: "The forelocks of horses contain good until the Day of Judgement. The horse is for three (purposes): It is for one man a reward, and it is for one man a shelter (from poverty), and it is from one man a burden. As for the one who acquires it for the cause of Allah and then prepares it for that; it is for him a reward, nothing disappears into its stomach except that Allah writes it for him as a reward." [Abu 'Eisa said:] This Hadith is Hasan Sahih. Malik bin Anas narrated similar to this Hadith from Zaid bin Aslam from Abu Salih from Abu Hurairah, from the Prophet (ﷺ)