The Law Code of Nārada v12.110

Nāradasmṛti v12.110

savarṇo brāhmaṇīputraḥ kṣatriyāyām anantaraḥ /
ambaṣṭhograu tathā putrāv evaṃ kṣatriyavaiśyayoḥ //