One verse

Srimad Bhagavatam 9.18.5

9.18.5

श्रीराजोवाच ब्रह्मर्षिर्भगवान् काव्य: क्षत्रबन्धुश्च नाहुष: । राजन्यविप्रयो: कस्माद् विवाह: प्रतिलोमक: ॥ ५ ॥

sri-rajovaca brahmarsir bhagavan kavyah ksatra-bandhus ca nahusah rajanya-viprayoh kasmad vivahah pratilomakah

sri-raja uvaca
Maharaja Pariksit inquired
brahma-rsih
the best of the brahmanas
bhagavan
very powerful
kavyah
Sukracarya
ksatra-bandhuh
belonged to the ksatriya class
ca
also
nahusah
King Yayati
rajanya-viprayoh
of a brahmana and a ksatriya
kasmat
how
vivahah
a marital relationship
pratilomakah
against the customary regulative principles.

Maharaja Pariksit said: Sukracarya was a very powerful brahmana, and Maharaja Yayati was a ksatriya. Therefore I am curious to know how there occurred this pratiloma marriage between a ksatriya and a brahmana.