Mahatma Vidur was in a way an incarnation of Dharma. Due to the curse of the sage, Mandavya, he was to be born in the Shudra caste. He was born to the maid of the king Vichitravirya. Thus, he was the real brother of Pandu and Dhritarashtra. He was very prudent, wise, polite, religious, well mannered and devoted to the Lord. As a minister to Dhritarashtra, he used to give him good advice. When Duryodhana was born, he had cried like a jackal. Seeing all these bad omens, Vidur had cautioned Dhritarashtra that his child would be the cause of the Kauravas destruction, hence it would be better to abandon the child at once. But due to the attachment for his child, Dhritarashtra did not pay heed to his advice and as a result suffered a lot all along his life just because of Duryodhana.

Because of Duryodhana's atrocities, Mahatma Vidur developed sympathy for the Pandavas and he helped them and protected them directly or indirectly. He knew that despite any crisis, the Pandavas would win the battle eventually. They were blessed with a long life and hence no one could kill them. That is why Vidur advised Kunti to keep calm and not to protest when Duryodhana had craftily poisoned Bheema and had thrown him into a river. He cautioned her that if she raised her voice to protest against Duryodhana's treachery against Bheema, then he would get irritated and he would attempt to kill the other Pandavas in the same manner. As for Bheema, Vidur convinced Kunti that he would escape unhurt. Kunti was convinced of Vidur's words as she knew that he was a man of truth and indeed he came back safe and sound.

Vidur had also cautioned Yudhishtir of the imminent danger that was lurking in Barnavata and also told him the way to escape the danger. It was Vidur who had planned the digging of a tunnel from Lakshagriha to the bank of the Ganges and had arranged for the boat to emerge on the river and finally cross it. Thus acting prudently, Vidur saved the lives of the Pandavas. Vidur did not discriminate in his affection for the Pandavas and the Kauravas and he used to give them good advice as well. But Duryodhana never liked his advice. Even then, Vidur tried his level best to put his brother Dhritarashtra on the right track. But under the influence of his sons, Dhritarashtra never followed Vidur's advice but assuming him to be his well wisher, he always sought Vidur's advice.

Following Shakuni's advice, Duryodhana informed the proposal of inviting the Pandavas over a game of dice. Vidur cautioned Dhritarashtra that such a game would only increase the enmity between the two sides, hence a game of dice is inauspicious for both the sides. Praising Vidur, Dhritarashtra then persuaded Duryodhana to give up the plan. But Duryodhana was determined to humiliate the Pandavas, hence he made Dhritarashtra accept his plan. It was Vidur who went to Indraprastha with the proposal of the game. Yudhishtir too did not like the game of dice but lest his uncle's desire be dishonoured, he also accepted Duryodhana's proposal. Even when the game was being played, Vidur tried to convince Dhritarashtra that he still had enough of time to come around and drop his submissive stance for Duryodhana and save his clan and not to make the Pandavas their enemy.

After the Pandavas had left for exile, Dhritarashtra was worried as to how to convince the subjects and how to please the Pandavas to return. Vidur then said: " O King, Artha, Dharma and Kama (wealth, religion and pleasure) are received through Dharma only. Dharma is the pedestal of the state. Hence, you should protect yourself and the Pandavas. Your sons have snatched everything from the Pandavas. It is against the Dharma. Hence, you should first get Duryodhana arrested and hand over the kingdom to Yudhishtir. Yudhishtir has no envy or jealousy, hence he will rule the kingdom religiously. Ask Dushasana to beg for pardon from Draupadi and Bheema in the court. Doing these things, you will be free from your worries, O King." But Dhritarashtra did not like this advice and saying that he always took the Pandavas side, he told Vidur as to how he could give up his sons just for the Pandavas sake." And thus he ordered Vidur to leave. Anticipating the imminent fall of the Kauravas, Vidur visited Kamyaka Vana to meet the Pandavas and told them a few things for their benefit. There, in the palace, Dhritarashtra came to know of Vidur's visit to the Pandavas and began to suspect that with the help of Vidur, the Pandavas would become stronger. So through Sanjay, he called Vidur back and begged him for pardon. At that Vidur told Dhritarashtra that he did not differentiate between the Kauravas and the Pandavas but seeing the Pandavas in such a hapless condition, it was but natural to help them, in any case, he did not have any partiality for the Kauravas.

Once Dhritarashtra was having a sleepless night. So calling Vidur, he sought the way for solace. The preaching which Vidur delivered during that time is even today known as Vidur Niti. But even such a beautiful preaching failed to pacify Dhritarashtra, for he wanted to know some other thing. Then, Vidur called the son of Brahma, the sage Sanatsujata and begged him to preach Dhritarashtra about the cosmic appearance of Paramatma and how to see him. Had he wished then, Vidur himself would have preached Dhritarashtra but as he belonged to the Shudra class, he did not want to show disregard for the scriptures norms.

Vidur was also very loyal to Lord Krishna. When Krishna came to Hastinapur with the peace proposal, he preferred to stay with Vidur relishing the plain food offered by him in contrast to the royal meal, which was being served at the palace. It is thus easy to guess the intense love of Lord Krishna for Vidur. Next day when Duryodhana tried to tie Krishna in the palace, Vidur cautioned him and told him that Shri Krishna is the Lord Himself and any kind of disrespect for him would destroy him like a flame destroys a moth. Thereafter the Lord appeared in his cosmic form and seeing which all except Vidur, Bheeshma, Sanjay and Drona closed their eyes. The Lord had given a few fortunate ones the opportunity to see the divine sight of the Lord in cosmic form. Then Lord Krishna came back to Upapalavya

After the battle was over, Vidur consoled Dhritarashtra that whoever died in the battle had attained salvation, hence one should not mourn for them. Every time a human is born, he makes new relations but after his death these relations crumble like a castle made out of sand crumbles. Hence, it is useless to mourn for the dead relatives. Events like comforts and miseries, crisis and fortune and misfortune etc. is due to the result of one's own good or bad deeds. Every living being has to bear the fruits of his deeds. Thereafter Vidur preached the ways of observing the right conduct and how to be rid of the miseries.

After the coronation of Yudhishtir, Dhritarashtra came to stay with him. Vidur also stayed with him and used to be engaged in religious discussions. Eventually, he accompanied Dhritarashtra, Gandhari and Kunti in their penance. In the forests, observing solitude, he observed severe penance. Once Yudhishtir went to the forests to meet his mother, uncle and aunt. Not finding Vidur there, he inquired about him. At that time Vidur was heading for his hermitage far away in the jungles. Yudhishtir called out to him several times but Vidur did not pay any notice to his calls and he stood resting against a tree. Yudhishtir hastily went near Vidur and found out that due to his severe penance, Vidur's body had been reduced to a mere skeleton. There and then, Yudhishtir worshipped him and saw a beam of light emerging from his body and annihilated in Yudhishtir and the lifeless body of Vidur remained resting against the tree. Thus living a religious life, Vidur attained salvation.