Skandapurana 5.22.13

5.22.13

ditiścaivā'dadhādgarbhaṃ kaśyapānmunipuṃgavāt ..
tataḥ śakro bhayaṃ cakre jñātvā taṃ garbhasaṃbhavam..
vadato munimukhyasya nāradasya mahātmanaḥ .. 13 ..

And Diti conceived an embryo from Kaśyapa, the foremost of sages. / Then Śakra felt fear, having learned of that conception / as the noble Nārada, the chief of sages, told of it.