Bhagavatapurana 9.4.22

9.4.22

īje 'śvamedhairadhiyajñamīśvaraṃ mahāvibhūtyopacitāṅgadakṣiṇaiḥ /
tatairvasiṣṭhāsitagautamādibhir dhanvanyabhisrotamasau sarasvatīm //

22. He worshipped the Lord of sacrifices, the Supreme Ruler, by means of extensive Aswamedha sacrifices in which the rites were well conducted and dakshinas given on a very large and splendid scale worthy of his wealth and, under the direction of Vasishta, Gautama and others, he performed them in a desert place so well as to make the river Saraswati flow (backwards) towards it.