When Vamana assumed the form of Trivikrama, He measured the world with one foot. His other foot reached Brahma Loka. Brahma washed His foot, and this water became the sacred Ganga river. Mahabali’s son Namuchi held on to the Lord’s foot, thinking he could keep the Lord from measuring land with His large feet. But the Lord swirled Namuchi away to the sky and continued to grow. Watching the Lord expand in height, Mahabali thought perhaps the Lord would stop once he reached one of the three lokas which Bali ruled over. But the Lord went beyond these lokas and covered seven lokas. His stamp was now on everything. When there was nothing left for the Lord to measure, He asked Mahabali where to put His foot to measure the third portion of land promised to Him. Mahabali indicated his head, and the Lord pressed Bali down to patala loka, where he was to be ruler. Mahabali was not a great sage or devotee. But what good fortune he had to have the Lord place His foot on his head! This is a blessing His bhaktas crave for, said M.A. Venkatakrishnan, in a discourse.
Mahabali usurped Indra’s territory. Taking something that did not belong to him was the wrong that Mahabali committed. But he had always been generous. That is why he was banished to the netherworld, which he was to rule. Suppose a child in our family takes a toy belonging to the neighbour’s child, and this leads to a row, we take the toy away from our child and return it to the neighbour’s child. But we also console our child by saying that we will get it a better toy later. In the same vein, the Lord returned Indra’s kingdom which Bali had taken, but He gave Bali unchallenged control over another loka. Like Aswattama and Vyasa, Mahabali too is a Chiranjeevi, that is, an immortal being.