BALI The (demon) king Bali was inflated with ego because of his wealth. With great pride, he performed Yajnas (sacrificial feasts). Without getting the advice of the Guru, he was sent to the nether-world. (Gauri M. l, p. 224) (Vishnu as) Vamana had asked for only two and a half steps of earth (from Bali) ostentatiously. If Bali had comprehended Vishnu\’s form, why should he have been deceived and thrust into the nether-world? (Prabhati M. l, p. 1344) Bali, the demon king was the son of Virochana, grandson of Prahlada and great grandson of Hiranyakashipu.
He was a good and virtuous king and through his devotion and austerities, he became very powerful. He humiliated the gods and defeated Indra, who went to Vishnu for help. Vishnu assumed the form of a dwarf (Vamana) and asked Bali for a boon of two and a half steps. When the boon was granted, Vishnu enlarged himself to such a big size that in two strides, he stepped over the heaven and earth.
Because of Bali\’s kindness, Vishnu with his next step thrust him into the nether-regions and made him the king of Patala. The legend generally mentions three steps instead of two and a half steps. The germ of the legend or three steps is found in the Rig Veda. It is said that Shukra, the priest and preceptor of Bali asked him to deal cautiously with the dwarf, but because of his kind nature, the demon king granted the boon to the dwarf (the Vishnu incarnation). See : Das Avatars Vishnu Incarnation
1. Kohli, Surindar Singh, Dictionary of Mythological References in Guru Granth Sahib, 1993