'Reward' in the Bible

Now the one who plants and the one who waters are one, but each one will receive his own reward according to his own labor.

If anyone's work that he has built upon [it] remains, he will receive a reward.

For if I do this voluntarily, I have a reward, but if [I do so] unwillingly, I have been entrusted with a stewardship.

What then is my reward? That [when I] proclaim the gospel, I may offer the gospel free of charge, in order not to make full use of my right in the gospel.