From Nagarjuna's Treatise on the Great Perfection of Wisdom
(Dharmamitra Translation)

A case in point is that of Shakyamuni Buddha who once was a six-tusked white elephant. A hunter had ambushed him and shot him with poison arrows. The herd of elephants stampeded towards him with the intention of trampling the hunter to death. The white elephant used his own body to defend him, protecting that man and having pity upon him just the same as if he was his own son. He ordered the herd of elephants away and then calmly asked the hunter, "Why did you shoot me?"

He replied, "I need your tusks." Immediately then, blood and flesh spontaneously pushed forth all six tusks from their sockets. He then used his trunk to pick up the tusks and give them to the hunter. Although it is described as the body of an elephant, in a case where the mind is used in this manner one should know that this elephant did not exist on account of retribution for the actions of an animal. Nowhere in the Dharma of the arhat is there a mind of this sort. One should realize that this is a Dharma body bodhisattva.