From Nagarjuna's Treatise on the Great Perfection of Wisdom
This is also illustrated by [the story of] Prince Candraprabha who had gone out sightseeing when a leper noticed him, presented himself at the carriage and addressed him, saying, "My body has come down with a serious disease which causes intense suffering and causes me to be grievously tormented. The prince is traveling about for pleasure. Will he only bring happiness to himself? May he bring forth great loving-kindness and bring pity to mind. Pray, may I receive a cure that will rescue me?" When the Prince heard him, he asked the physicians about this matter. The physician replied, "It would be necessary to obtain the blood and marrow of a man who from the time of birth had grown up without any hatred. It would be topically applied and also drunk. If one proceeded in this fashion, then he could be cured."
The Prince thought to himself, "If there is such a person, he is desirous of living and cherishes his own life. How could such a person be obtained? Aside from myself, there is no place where he could be found." He then issued an order for a ca.n.daala to come and instructed him to strip away flesh from his body, break his bones, extract his marrow, smear it on the body of the sick man, and then take his blood and provide it as a drink for him.