Mahabharata Anushasna Parva Chapter 148:4

Mahabharata Anushasna Parva (Dana Dharma Parva) Chapter 148:4 One that becomes even desirous of listening to that discourse should worship Mahadeva with reverence. Verily, the person that wishes to obtain what is beneficial for him, should adore Mahadeva with a pure heart. Even this is the command of the faultless and high-souled Narada. Even he has commanded such worship of the great god, O son of Pandu, do thou obey that command of Narada. O puissant king, even these are the wonderful incidents that occurred on the sacred breast of the Himavat respecting Vasudeva and Sthanu, O son of Kunti. Those occurrences flowed from the very nature of those high-souled deities. Vasudeva, accompanied by the wielder of Gandiva, practised eternal penances in the retreat of Vadari for ten thousand years.[] Verily, Vasudeva and Dhananjaya, both of eyes like lotus-petals, underwent severe austerities for the duration of three whole Yugas. I have learnt this from Narada and Vyasa, O king. The lotus-eyed and mighty-armed Vasudeva, while yet a child (in human form) achieved the great feat of slaying Kansa for the relief of his kinsmen. I do not venture, O son of Kunti, to enumerate the feats of this Ancient and Eternal Being, O Yudhishthira. Without doubt, O son, high and great benefits will be reaped by thee who ownest that foremost of all persons, viz., Vasudeva, for thy friend. I grieve for the wicked Duryodhana in respect of even the next world to which he has gone. It was for him that the whole earth has been depopulated with her steeds and elephants. Indeed, through the fault of Duryodhana, of Karna, of Sakuni, and of Duhsasana numbering the fourth, that the Kurus have perished." "Vaisampayana continued, 'While that foremost of men, viz., the son of Ganga, addressed him in this strain, the Kuru king (Yudhishthira) remained entirely silent in the midst of those high-souled persons (who had assembled together for listening to the discourses of Bhishma). All the kings with Dhritarashtra amongst them became filled with wonder upon hearing the words of the Kuru grandsire. In their minds they worshipped Krishna and then turned towards him with hands joined in reverence. The Rishis also with Narada at their head, accepted and applauded the words of Bhishma and approved of them joyfully. These were the wonderful discourses recited by Bhishma which Pandu's son (Yudhishthira) with all his brothers heard with joy. Some time after, when king (Yudhishthira) saw that Ganga's son who had given away abundant wealth as presents unto the Brahmanas in the sacrifices performed by him, had rested and become refreshed, the intelligent king once more asked him as follows.'"