Vishnupurana 4.7.5

4.7.5

jahnoś ca sumantur nāma putro 'bhavat |
tasyāpy ajakas tato balākāśvas tasmāt kuśaḥ kuśasya kuśāmbakuśanābhāmūrtarayāmāvasavaś catvāraḥ putrā babhūvuḥ ||

The son of Jahnu was Sumantu; his son was Ajaka; his son was Valákáśwa; his son was Kuśá, who had four sons, Kuśámba, Kuśanábha, Amúrttaya, and Amávasu. Kuśámba, being desirous of a son, engaged in devout penance to obtain one who should be equal to Indra. Observing the intensity of his devotions, Indra was alarmed lest a prince of power like his own should be engendered, and determined therefore to take upon himself the character of Kuśámba's son. He was accordingly born as Gádhi, of the race of Kuśa (Kauśika). Gádhi had a daughter named Satyavatí. Richíka, of the descendants of Bhrigu, demanded her in marriage. The king was very unwilling to give his daughter to a peevish old Brahman, and demanded of him, as the nuptial present, a thousand fleet horses, whose colour should be white, with one black ear. Richíka having propitiated Varuńa, the god of ocean, obtained from him, at the holy place called Aśwatírtha, a thousand such steeds; and giving them to the king, espoused his daughter.