SB 3.1.8
dyute tv adharmena jitasya sadhoh
satyavalambasya vanam gatasya
na yacato ’dat samayena dayam
tamo-jusano yad ajata-satroh
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Yudhisthira, who was born without any enemy, was unfairly defeated in gambling. But because he had taken the vow of truthfulness, he went off to the forest. When he came back in due course and begged the return of his rightful share of the kingdom, he was refused by Dhrtarastra, who was overwhelmed by illusion.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Maharaja Yudhisthira was the rightful heir to his father’s kingdom. But just to favor his own sons, headed by Duryodhana, Dhrtarastra, Maharaja Yudhisthira’s uncle, adopted various unfair means to cheat his nephews of their rightful share of the kingdom. At last the Pandavas demanded only five villages, one for each of the five brothers, but that was also refused by the usurpers. This incident led to the War of Kuruksetra. The Battle of Kuruksetra, therefore, was induced by the Kurus, and not the Pandavas.
As ksatriyas, the proper livelihood of the Pandavas was only to rule, and not to accept any other occupation. A brahmana, ksatriya or vaisya will not accept employment for his livelihood under any circumstances.