Anushasana Parva 138.46

The Ascetics said You should, O Narada, describe in full, from the beginning, to Hrishikesha, that wonderful and inconceivable incident which took place, O powerful one, on the mountains of Himavat and which, O 'ascetic, was seen by those of us who had gone there in course of our sojourn to the sacred waters. Indeed, for the behoof of all the Rishis here collected, you should recite that incident.