Vajrasuci (Siddhacarya Ghoshapada) 26

26

caṇḍālīgarbhasambhūto viśvāmitro mahāmuniḥ
tapasā brāhmaṇo jātastasmājjātirakāraṇam

The great sage Viśvāmitra was born from the womb of a caṇḍāla woman;
he became a brāhmaṇa through austerity; therefore, birth is no cause.