“Ganga said. ‘O great king! what dost thou desire of me? And what must I bestow on thee? Tell me the same, O most praiseworthy of men! I shall do as thou mayst ask me.’ Thus addressed, the king then made his reply to Ganga, the daughter of the snowy Hill, saying, ‘O grantress of boons! O great river! my father’s fathers, while searching for the horse, were sent by Kapila to the abode of the god of death.

In plain words: Ganga asked the king what he wanted and promised to give it. The king said his great-grandfathers, while searching for a lost horse, had been sent to the land of death by the sage Kapila.