Matsya Purana 198.9

198.9

tathā vai deharātā ye kuśikāśca narādhipa!.
tryārṣeyo'bhimatasteṣāṃ sarveṣāṃ pravaraḥ śubhaḥ .. 198.8

They also do not intermarry among themselves. Daivaśravâ, Devarâta ; Viśvâmitra are the three Pravaras of Daivaśravâ, Sujâtaiyâ, Sansukâ, Kârukâya, Vaidaiharatâ, Kuśikâ. They also do not intermarry. Dhananjaya, Kapardaiya, Parîkûta, Pârthiha, Pânini have Viśvâmitra, Madhuchchhanda, Aghamarṣaṇa for their Pravaras. They also do not intermarry. Kamalâyajina, Aśmarathya, Bânjuli, are also the three Pravaras. They too do not intermarry.—7-14.