The Vaman Avatar, incarnation of Lord Vishnu as Vaman

In the ancient age the famous demon king Bali asked his guru Shukracharya to give him a solution to defeat the Devas, the inhabitants of heaven. Shukracharya advised him to perform the Biswajit Yajna (विश्वजीत यज्ञ, a difficult oblation) to achieve enormous power to defeat the Devas and Bali performed the Yajna strictly following the rules. After completion of the oblation, a miraculous chariot with four horses appeared from the fire as a reward. Boarding the chariot Bali along with his demon force surrounded the heaven to acquire it from the Devas. Realizing the extraordinary strength of the demons Devas asked Brihaspati to find a solution to the problem and advised by the guru to leave heaven in disguise because of the miraculous power of the chariot of Bali. He also criticized the Devas for their excessive indulgence in enjoyment without performing any Yajna to keep their strength growing and advised them to go to the mother of Devas Aditi, known as the Devmata. As described in scriptures. Diti and Aditi were two daughters out of many daughters of Prajapati Daksha. Both the sisters were married to Maharishi Kashyap. Diti gave birth to all the Demons and Aditi gave birth to all the Devas through Kashyap. On the advice of their guru, Devas went to Aditi and seeing their miserable condition she prayed to her husband to give her a son who would be able to defeat the Demons and return the glory of the Devas. Kashyap explained to her that by the power of the Biswajit Yajna demons have become undefeatable and it would take a long time to get a son who could defeat the Demons and advised her to perform a very difficult puja (worship) to appease Lord Srihari(Narayan) to fulfil her wish. Aditi started the worship on the designated auspicious day by following severe austerity for one year. One day Lord Srihari appeared before her in the form of a Vaman (dwarf) brahmachari(ब्रह्मचारी, celibate). His complexion was glowing light black having eyes like lotus and two hands. He was wearing a sylvan garland. Both Aditi and Kashyap were surprised to see Lord Srihari in the form of a dwarf brahmachari. This incarnation of Lord Srihari is popularly known as Vaman Avatar. Kashyap and Aditi sang the hymn of the glory of the Lord and the Lord told them he had accepted the prayer of Aditi and descended as her son to do the needful for the overthrown Devas. At that time Lord Brahma came and gave him the sacred thread (जनेयु) and made him a brahmin. 

        In the meantime when the Demons entered into heaven, they found the heaven empty as the Devas had fled in disguise. Their guru Shukracharya performed the rituals and consecrated (अभिषेक) Bali to the throne of heaven‌ and declared him the king of heaven in presence of Rishis, Gandharv(गन्धर्व), Kinnar ( किन्नर), Nagas (नाग) and demons. So Bali became the new Indradev of heaven and ruled the universe performing the role of sun, moon etc with the help of his miraculous power. One day Bali decided to stay in heaven forever along with all the Demons. So he ordered all the Demons to shift to heaven from the abyss (पाताल) permanently, but Shukracharya explained to him that he wouldn't be able to stay in heaven forever unless he acquired the eligibility to become the Indradev by performing one hundred Ashwamedha Yajna (अश्वमेध यज्ञ) and that too in India(भारत-वर्ष). So Bali along with the demons came to India and camped on the bank of river Narmada which is known as Bhrigukachh, a holy place. From there he attacked the kings of the earth and defeated all of them and became the emperor of the world. After that, he took the permission of his guru Shukracharya and commenced the Ashvamedha Yajna fulfilling all the ritualistic requirements and finished ninety-nine Ashwamedha Yajna. By that time Lord Srihari had already taken Vaman Avatar. When Bali started the hundredth (final) Yajna for acquiring heaven permanently, Lord Vaman came to him and praised the ancestors of Bali. Seeing him Bali bowed before him and asked the wish of the Lord, he took an oath to fulfil his wish at any cost. At that time Shukracharya forbade Bali not to promise anything and told him that the Vaman was none other than Lord Srihari, the all-pervading Supreme Soul(परमात्मा) who in the form of Mohini had ditched the Demons from drinking nectar and also who had come on behalf of the Devas to regain the heaven from Bali. But the demon king refused to obey the order of his guru Shukracharya as he was a devotee of Lord Srihari and wanted to sacrifice his life on the feet of the Lord. Bali's disobedience infuriated Shukracharya and as a result, he cursed him and left the place of worship. Then the Lord asked Bali to give him a space measuring trice the size of his one foot. Bali was surprised to hear the wish of the Lord and urged him to ask for a space as large as a country. But the Lord didn't change his wish. So Bali asked him to place his foot on the earth. Instantly the Lord's dwarf figure grew like a huge mountain. His first step covered the whole earth and the second step covered the whole sky and reached the Satyalok(सत्यलोक), the abode of Brahma. Brahma washed the foot of the Lord and kept the चरणामृत( washed water of the foot) in his pot(कमनडलू). In later stages, water flowed to the earth on the prayer of Bhagirath in the form of the holy river Ganga. Lord's first and second steps covered the whole earth and sky. Now he asked Bali to give him the space for putting his third step. Bali had no other option. So requested the Lord to place his third step on his head. Seeing the level of his dedication and sacrifice the Lord was very pleased and in return, he allotted him Sutal Lok (सुतललोक) to reside with his family and followers. But Bali prayed to the Lord to keep him as his servant to which the Lord said that he would stay as his gatekeeper (द्वारपाल) in the Sutal lok. From that day Bali is residing as the king of Sutal Lok and the Lord being omnipresent, staying with him as his gatekeeper. After that Lord Vaman handed over the heaven to the Devas and returned back to his abode Baikunth.

Shrimad Bhagwat Mahapuran