In the Vedic myth of Samudra Manthan (the churning of the ocean of milk), the gods (Devas) and demons (Asuras) worked together to obtain the nectar of immortality (Amrit). When Vishnu began distributing it, one Asura disguised himself as a Deva to drink the nectar. The Sun and Moon spotted him and alerted Vishnu, who instantly decapitated the Asura with his Sudarshan Chakra (divine discus).