'Reward' in the Bible

The one who plants and the one who waters have the same goal, and each will receive a reward for his own action.

If what a person has built on the foundation survives, he will receive a reward.

For if I preach voluntarily, I get a reward, but if I am unwilling to do it, I am still entrusted with that obligation.

What, then, is my reward? It is to be able to preach the gospel free of charge, and so I never resort to demanding my rights when I'm preaching the gospel.