Musannaf Ibn Abi Shayba 28:964

Waki’ narrated to us, he said: ‘Abd al-Hamid ibn Bahram narrated to us, from Shahr ibn Hawshab, from Asma bint Yazid, she said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever ties a horse in the way of Allah, and spends on it seeking reward, then its fullness and its hunger, and its thirst and its quenching, and its dung and its urine, will be in his scale on the Day of Resurrection. And whoever ties a horse for showing off and for reputation, that will be a loss in his scale on the Day of Resurrection."