The demon king Bali, grandson of Prahlad, was extremely generous and mighty. He had conquered the three worlds. The gods, worried, approached Lord Vishnu.
Vishnu took the form of a dwarf Brahmin named Vamana and came to Bali’s yajna. Bali welcomed him and said, “Ask for whatever you wish.” Vamana asked only for three paces of land.
Bali’s guru Shukracharya warned him that this was no ordinary Brahmin. But Bali stood by his word and said one must not step back when giving a gift.
Vamana grew so large that he measured the earth in one step and the sky in the second. There was no place left for the third. Bali bowed his head and said, “Lord, place your third step on my head.”
Vamana placed his foot on his head and gave Bali the realm of Sutala. Pleased with Bali’s devotion and loyalty to his word, the Lord also granted him a boon. In Kerala, Onam is linked to Bali’s annual visit.