Bhojājānīya Jātaka (No.23)
The Bodhisatta was once born as a thoroughbred horse and was made the war-horse of the king of Bārāṇasī. He was given every kind of luxury and was shown all honour. All the king’s around coveted the kingdom of Bārāṇasī, and seven kings encompassed the city. At the suggestion of his ministers, the king sent out a knight on the royal war-horse. Mounted on the noble steed, the knight destroyed six camps, when his horse was wounded. He thereupon took it to the gate, loosened its armour, and prepared to arm another horse. However, the animal, knowing that no other horse could accomplish what awaited him, insisted on attacking the seventh camp. Then when they brought him back to the king’s gate, the king came out to look upon him, and the horse died with a counsel for mercy towards the captive kings.
The story was told in reference to a monk who had given up persevering. Ānanda is identified with the king. J.i.178‑81.
Cp. the Ajañña Jātaka.