Mahabharata 2.20.26

2.20.26

kṣatriyasyaitadevāhurdharmyaṃ kṛṣṇopajīvanam |
vikramya vaśamānīya kāmato yatsamācaret || 26 ||

"Jarasandha said,--'I never make a captive of a king without first vanquishing him. Who hath been kept here that hath not been defeated in war? This, O Krishna, it hath been said, is the duty that should be followed by the Kshatriyas, viz., to bring others under sway by the exhibition of prowess and then to treat them as slaves. Having gathered these monarchs with the intention of offering them as sacrifices unto the god, how shall I, O Krishna, from fear liberate them to-day, when I recollect also the duty I have recited of a Kshatriya? With troops against troops arrayed in order of battle, or alone against one, or against two, or against three, at the same time or separately, I am ready to fight.'"