Bhagavatapurana 9.16.35

9.16.35

jyeṣṭhaṃ mantradṛśaṃ cakrustvāmanvañco vayaṃ sma hi /
viśvāmitraḥ sutān āha vīravanto bhaviṣyatha /
ye mānaṃ me 'nugṛhṇanto vīravantamakarta mām //

35. They adopted Sunassepa as their eldest brother, the seer of mantras, and said to him, “we are all thy younger brothers”; then Visvamitra said to his sons, “Be you blessed with children as you have maintained due respect (by your obedience) for me and have thus made me a father having (true) sons”. 36. O sons of Kusika race, this Devarata is one of you as my son and do you follow him. Visvamitra had also other sons, namely, Ashtaka, Hareeta, Jaya, Kratumat and others.