Gurudakshina is the gift a student owes the teacher at the end of study. In the Bhagavata Purana, Krishna and his brother Balarama study with the sage Sandipani. When they finish, Sandipani “asked for the restoration of his child, who had disappeared in the ocean at Prabhasa,” as Wikipedia summarizes. “He chose the return of his son who died at place called Prabhasa as the Gurudakshina,” another retelling of the Bhagavata says.