Puranic Encyclopaedia: A Comprehensive Dictionary with Special Reference to the Epic and Puranic Literature c7.111

c7.111

Then Pratīpa called his son Śantanu and told him : “Sometime back a divine woman came to me and I promised to wed her to you. Therefore, if any divine woman approaches you for a son you must accept her, and whatever she may do you must not object to that...”. Not long after this Pratīpa crowned Śantanu King and left for the forest, (Ādi Parva, Chapter 97).
7) Aṣṭavasus and Gaṅgā. While the wife of Dyau, one of the Aṣṭavasus (eight Vasus) was roaming about in the forest she saw Nandini (the divine cow) grazing with her calf near the āśrama of Vasiṣṭha, and she desired to have the cow to be presented to her intimate friend Jitavatī, the daughter of King Uśīnara. She informed her husband, Dyau about this desire of hers, and Dyau told his relations about it. Next day the Aṣṭavasus, in the absence of Vasiṣṭha at the āśrama, stole off Nandinī and her calf. When Vasiṣṭha returned to the āśrama the cow and calf were missing, and he divined the reason for it with his divine eyes. He cursed that the Aṣṭavasus be born as men on earth, and when they prayed for redemption from the curse Vasiṣṭha told them that they would be born as men within one year from that day, die at once and return to heaven. At the same time the sage said that Dyau alone, who took the leading part in stealing the cow, would live on earth for a longer period before he returned to heaven. (The reputed Bhīṣma was this Dyau). The Aṣṭavasus set out for the earth to be born as men and on their way they met Gaṅgā and told her about their curse etc. Gaṅgā also told them about her curse, and permitted them to be born in her womb. (Ādi Parva, Chapter 99).