Vishnupurana 4.7.9

4.7.9

tenāpy ṛṣ.iṇā varuṇasakāśād upalabhyāśvatīrthotpannaṃ tādṛgaśvasahasraṃ dattam |
tatas tām ṛcīkaḥ kanyām upayeme |
ṛcīkaś ca tasyāś carum apatyārthaṃ cakāra ||

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.

In order to effect the birth of a son, Richíka prepared a dish of rice, barley, and pulse, with butter and milk, for his wife to eat; and at her request he consecrated a similar mixture for her mother, by partaking of which she should give birth to a prince of martial prowess. Leaving both dishes with his wife, after describing particularly which was intended for her, and which for her mother, the sage went forth to the forests. When the time arrived for the food to be eaten, the queen said to Satyavatí, "Daughter, all persons wish their children to be possessed of excellent qualities, and would be mortified to see them surpassed by the merits of their mother's brother. It will be desirable for you, therefore, to give me the mess your husband has set apart for you, and to eat of that intended for me; for the son which it is to procure me is destined to be the monarch of the whole world, whilst that which your dish would give you must be a Brahman, alike devoid of affluence, valour, and power." Satyavatí agreed to her mother's proposal, and they exchanged messes.