SB 10.90.37

sa cāpi rukmiṇaḥ pautrīṁ
dauhitro jagṛhe tataḥ
vajras tasyābhavad yas tu
mauṣalād avaśeṣitaḥ

saḥ—he (Aniruddha); ca—and; api—furthermore; rukmiṇaḥ—of Rukmī; pautrīm—the granddaughter, Rocanā; dauhitraḥ—(Rukmī's) daughter's son; jagṛhe—took; tataḥ—then; vajraḥ—Vajra; tasya—as his son; abhavat—took birth; yaḥ—who; tu—but; mauṣalāt—after the pastime in which the Yadus slaughtered each other with iron clubs; avaśeṣitaḥ—remained.

Rukmī's daughter's son [Aniruddha] married Rukmī's son's daughter [Rocana]. From her was born Vajra, who would remain among the few survivors of the Yadus' battle with clubs.