Mbh 6.1.5b

And if having fought fairly the combatants withdraw (without fear of molestation), even that would be gratifying to us. Those who engaged in contests of words should be fought against with words. Those that left the ranks should never be slain.[7] A car-warrior should have a car-warrior for his antagonist; he on the neck of an elephant should have a similar combatant for his foe; a horse should be met by a horse, and a foot-soldier, O Bharata, should be met by a foot-soldier. Guided by considerations of fitness, willingness, daring and might, one should strike another, giving notice. No one should strike another that is unprepared[8] or panic-struck. One engaged with another, one seeking quarter, one retreating, one whose weapon is rendered unfit, uncased in mail, should never be struck. Car-drivers, animals (yoked to cars or carrying weapons), men engaged in the transport of weapons,[9] players on drums and blowers of conches should never be struck. Having made these covenants, the Kurus, and the Pandavas, and the Somakas wondered much, gazing at each other. And having stationed (their forces thus), those bulls among men, those high-souled ones, with their troops, became glad at heart, their joy being reflected on their countenances.”