The legend commemorated by the festival of Holi involves an evil king named Hiranyakashipu. He forbade his son Prahlad from worshipping Vishnu, but Radhu continued to do offer prayers to the god. Getting angry with his son, Hiranyakashipu challenged Prahlad to sit on a pyre with his wicked aunt Holika who was believed to be immune to fire. (In an alternate version, Holika put herself and Prahlad on the fire on orders from her brother.)