Musannaf Ibn Abi Shayba 28:965

Hussain bin Ali narrated to us, from Za'idah, from al-Rukayn, from Abu 'Amr al-Shaybani, from a man from the Ansar, from the Prophet (peace be upon him), who said: "Horses are of three types: A horse that a man keeps in the way of Allah; its price is a reward, its riding and its lending are a reward, and its fodder is a reward. A horse that a man keeps for gambling and betting; its price is a sin, its fodder is a sin, and its riding is a sin. And a horse for one's own needs (to cover expenses); it may be a protection against poverty, if Allah wills."