Aggrieved with the plight of her sons, the demigods, Aditi, the wife of Kasyapa Muni performed severe penance and practiced austerities with the goal of pleasing the Supreme Personality of God-head. Pleased with her devotion to him, the Supreme Personality of God-head promised to become her son to protect her other sons. He was then born in the form of Vamana, a brahmana dwarf, a brahmachari. During the sacred thread ceremony of Vamanadeva, he was presented with a begging bowl by Kubera, the lord of the yakshas.
Vamana then proceeded to the place where Bali was performing his sacrifices and yagna. Holding in his hands, the rod of a brahmachari, a wooden umbrella and a pot full of water, he entered the arena where the ashwamedha sacrifice was being held. Although he was just a young brahmana boy wearing a belt of straw, a sacred thread, an upper garment of deerskin with matted locks of hair, he generated such radiance and effulgence that everybody in the arena stood up to welcome him there.
Bali then offered him a seat and worshipped him by washing his feet. Being aware of the prevalent religious principles, he also placed his head on the feet of the young brahmachari.
Bali addressed him thus – O son of a brahmana, it appears that you have come here to ask me something. Therefore, whatever you want from me shall be given to you. This is my promise to you.
Pleased with the asura king’s benevolence, Vamana replied O king, I ask you only three paces of land to the measurement of my steps.
When Bali intervened and requested the brahmachari to ask for a more significant offering, Vamana replied O King, even the entire three worlds will not satisfy a person whose senses are uncontrolled. If I were not satisfied with three paces of land then I would surely not be satisfied if you gave me seven islands and more.
Sukracharya who by now suspected that there was more to this young brahmachari than met the eye, took Bali aside and told him – This is the Supreme Personality of God-head, incarnate as the son of Kasyapa Muni and Aditi. He has now appeared here to fulfill the interests of the demigods, and your promise to him has the possibility of bringing great harm to our asura brethren.
Understanding the full import of his spiritual guru’s words, Bali then replied stating that he had made a promise to the young brahmachari and intended to fulfill it, at whatever cost. Being the grandson of Prahlada, how could he go back on his promise to a young brahmana and be accused of being untruthful.