Vana Parva 82.87

The Rishis, the Pitris, the Devas, the Gandharvas, the Apsaras, the Guhyakas, the Siddhas, the Vidyadharas, the men. The Rakshashas, the Daityas, the Rudras, the Brahma himself, O ruler of men, having their senses subdued and having performed austere asceticism for one thousand years. In order to secure the grace of Vishnu, cooked Charu here and gratified Keshava (Vishnu) with oblation (offered), each time uttering seven Riks (the verse of three Vedas).