Mahabharata 1.1.55

1.1.55

utpādya dhṛtarāṣṭraṃ ca pāṇḍuṃ vidurameva ca |
jagāma tapase dhīmānpunarevāśramaṃ prati || 55 ||

"Sauti continued, 'I will now speak of the undying flowery and fruitful productions of this tree, possessed of pure and pleasant taste, and not to be destroyed even by the immortals. Formerly, the spirited and virtuous Krishna-Dwaipayana, by the injunctions of Bhishma, the wise son of Ganga and of his own mother, became the father of three boys who were like the three fires by the two wives of Vichitra-virya; and having thus raised up Dhritarashtra, Pandu and Vidura, he returned to his recluse abode to prosecute his religious exercise.