Lord Vishnu opened the gate of Vaikuntham (his abode) for two asuras (demons) in spite of their being against him. They also asked for the boon that whoever listens to their story and sees the image of Vishnu coming out of the door called Vaikunth Dwar, will reach Vaikunth as well. Temples all over India make a door kind of structure on this day for devotees to walk through.