The son of Triśaṅku was Hariścandra. Because of Hariścandra there was a quarrel between Viśvāmitra and Vasiṣṭha, who for many years fought one another, having been transformed into birds.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
त्रैशङ्कवो हरिश्चन्द्रो विश्वामित्रवसिष्ठयोः । यन्निमित्तमभूद्युद्धं पक्षिणोर्बहुवार्षिकम्
traiśaṅkavo hariścandro viśvāmitravasiṣṭhayoḥ | yannimittamabhūdyuddhaṃ pakṣiṇorbahuvārṣikam
SB 9.7.7