Mbh 1.175.2c

And Tapati of fair eyebrows came down from the firmament like lightning from the clouds, dazzling the ten points of the heavens. And the illustrious Rishi Vasishtha of pure soul approached the monarch after the latter’s twelve nights’ vow was over. It was thus that king Samvarana obtained a wife after having worshipped with like the full moon. And that mighty bowman, that foremost one in Kuru’s race having his curiosity greatly excited by what he heard of Vasishtha’s ascetic power, asked the Gandharva, saying, ‘I desire to hear of the Rishi whom thou hast mentioned as Vasishtha. O, tell me in full about him! O chief of the Gandharvas, tell me who this illustrious Rishi was that was the priest of our forefathers.’ The Gandharva replied, ‘Vasishtha is Brahma’s spiritual (lit, mind-born) son and Arundhati’s husband. Ever difficult of being conquered by the very immortals, Desire and Wrath, conquered by Vasishtha’s ascetic penances, used to shampoo his feet. Though his wrath was excited by Viswamitra’s offence, that high-souled Rishi did not yet exterminate Kusikas (the tribe whose king Viswamitra was). Afflicted at the loss of his sons, he did not, as though powerless, though really otherwise, do any dreadful act destructive of Viswamitra, Like the ocean transgressing not its continents, Vasishtha transgressed not (the laws of) Yama by bringing back his children from the domains of the king of the dead. It was by obtaining that illustrious one who had conquered his own self that Ikshvaku and other great monarchs acquired the whole earth. And, O prince of Kuru’s race, it was by obtaining Vasishtha, that best of Rishis as their priest, that those monarchs performed many grand sacrifices. And, O best of the Pandavas, that regenerate Rishi assisted these monarchs in the performance of their sacrifices like Vrihaspati assisting the immortals.