Jay and Vijay cursed

Markandeya said Listen Yudhistira while I tell you the story. I will tell you what happened before this. In Vaikuntha, Vishnu resided. He had two brothers who guarded his doors. The elder one was Jay and the younger one was Vijay. One day they stopped a brahmana from entering. Angry, the brahmana cursed them to be born on the earth.
The brothers told this to Vishnu. Vishnu said : The brahmana should not have been stopped. There is nothing I can do about the curse. You will be born on the earth as per the curse.
The brothers then said How many years would they have to live like that, away from Vaikuntha?
Vishnu said If you are on earth and you become my disciple then you will have to go through seven births and deaths before you are back here. If, you become my enemies, then you will have to go through three births and deaths and you will return then. Do not worry, I will also be born to be with you.
The brothers agreed for the later.
At that time, Diti, wife of Sage Kashyapa, was praying for a son. She went to her husband asking for a son to be born to her. The sage said The time when you have approached me is an extremely inauspicious time. The son born to you will be evil.
Diti said she was ready for the consequences.
Kashyapa said you will have twins. They will grow up and become evil. Vishnu will be born and will kill your sons with own hands. You will also suffer grief for the loss of these sons.
Jay and Vijay were then born as the twin sons of Diti.
The earth trembled when they were born.