Vishnu blessings and birth of Onam

For the devotion of the daitya, Mahabali, Lord Vishnu Vamana granted him rule over the underworld. It was also granted that he would hold the position of Indra for one Manvantara a cyclic measure of time, thus fulfilling his devotee desire the office of Indra was a rotating position, changing every Manvantara.As a last gift, Mahabali was granted permission to visit his subjects once a year. Thus, Keralites celebrate the Onam festival to commemorate the memory of the Great King Mahabali who would keep his promise to visit them every year. Mahabali fulfilled his name as the great martyr for the sake of Truth Satya. The name Mahabali itself means Great Sacrifice.During Onam, the feast and festive mood of the people, dressed in their best, is considered reminiscent of the prosperous and truthful life of the subjects during Mahabali flawless reign. People wear new clothes Vastra during Onam. The Vastra also stands for heart. Thus the significance of wearing new clothes is about making the heart new by removing all bad thoughts and feelings.