Vishnu and Shiva - Sudarshana chakra
Many years ago, the demons oppressed the gods and the gods went to Vishnu for deliverance. Vishnu said that the demons were so powerful, that he would first have to worship Shiva if something was to be done about the asuras. Vishnu went to Mount Kailasa and bean to pray to Shiva. He chanted many mantras, but there was no sign of Shiva. Shiva has a thousand names and Vishnu next started to chant these names. Each day he chanted the thousand names and offered a thousand lotus flowers to Shiva.
Shiva decided to test Vishnu. One day, he stole a lotus flower from the thousand that were to be offered. When Vishnu realized that there was one lotus flower less, he gouged out his own eye and offered it in place of the missing lotus flower. Shiva was now pleased and appeared before Vishnu. He offered to grant Vishnu a boon.
You know that the powerful demons have been oppressing the gods, said Vishnu. I need a weapon to fight the demons with. Please give me a weapon.
Shiva then gave Vishnu the sudarshana chakra. And with this weapon, Vishnu killed the demons.
OM NAMO NARAYANAYA