菩薩過去生化為一頭烏黑公牛，被一老婦如子撫養；他曾助一商人拉車渡河，商人事後食言只付一半酬勞，牛便堅持不動直至如數付清。

The Bodhisatta in a past life as a jet-black bull, reared by a devoted old woman, who helped a merchant pull his carts across a ford and, after being cheated of half his promised wage, refused to move until paid in full.