Musnad Ahmad 596:8

Yazid ibn Abd Rabbih narrated to us, he said: Muhammad ibn Harb narrated to us, he said: al-Zubaydi narrated to us, from Rashid ibn Sa’d, from Abu ‘Amir al-Hawzani, from Abu Kabshah al-Anmari: that he came to him and said: "Lend me your horse, for I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever lends a Muslim a horse to ride, and it is used for the sake of Allah, he shall have the reward of seventy horses carried upon in the way of Allah.'"