Mbh 13.36.1

"'Bhishma said, "In this connection is cited the old history of the discourse between Sakra and Samvara. Do thou listen to it, O Yudhishthira. Once upon a time Sakra, assuming the guise of an ascetic with matted locks on his head and body smeared with ashes all over, rode on an ugly car and repaired to the presence of the Asura Samvara.