Mbh 1.109.2b

And the wheel of virtue having been set in motion by Bhishma, and the country became so contented that the subjects of other kingdoms, quitting their homes, came to dwell there and increase its population. And the citizens and the people were filled with hope, upon seeing the youthful acts of their illustrious princes. And, O king, in the house of the Kuru chiefs as also of the principal citizens, ‘give’, ‘eat’ were the only words constantly heard. And Dhritarashtra and Pandu and Vidura of great intelligence were from their birth brought up by Bhishma, as if they were his own sons. And the children, having passed through the usual rites of their order, devoted themselves to vows and study. And they grew up into fine young men skilled in the Vedas and all athletic sports. And they became well-skilled in the practice of bow, in horsemanship, in encounters with mace, sword and shield, in the management of elephants in battle, and in the science of morality. Well-read in history and the Puranas and various branches of learning, and acquainted with the truths of the Vedas and their branches they acquired knowledge, which was versatile and deep. And Pandu, possessed of great prowess, excelled all men in archery while Dhritarashtra excelled all in personal strength, while in the three worlds there was no one equal to Vidura in devotion to virtue and in the knowledge of the dictates of morality. And beholding the restoration of the extinct line of Santanu, the saying became current in all countries that among mothers of heroes, the daughters of the king of Kasi were the first; that among countries Kurujangala was the first; that among virtuous men, Vidura was the first; that among cities Hastinapura was the first. Pandu became king, for Dhritarashtra, owing to the blindness, and Vidura, for his birth by a Sudra woman, did not obtain the kingdom.