The Art of War by active 6th century B.C. Sunzi

16. Now in order to kill the enemy, our men must be roused to anger;

that there may be advantage from defeating the enemy, they must have their rewards. [Tu Mu says: "Rewards are necessary in order to make the soldiers see the advantage of beating the enemy; thus, when you capture spoils from the enemy, they must be used as rewards, so that all your men may have a keen desire to fight, each on his own account."]