Vishnu's guardians Jaya-Vijaya, were cursed by 4 kumara sages (Bramha's sons) to incarnate on Earth either 3 times as enemies of Lord Vishnu OR 7 times as devotees of Lord Vishnu. They chose to take birth on earth 3 times. In the first birth (During Satya Yuga), they were born as Hiranyakashipu and Hiranyaksha. In the second birth (During Treta Yuga), they were born as Ravana and Kumbhakarna. In the third birth (During Dwapara Yuga), they were born as Shishupala and Dantavakra. The references are from stories of Bhagavata Purana.