I got into a interesting discussion on the merits of fasting on my blog and a certain verse was the topic, see here in Matthew were Jesus confronts the idea of the pharisees fasting...

And again up came my issue with literalism .. cuz here’s the interesting thing — in that passage, even in the Greek, the word “reward” is used as the verb of the sentence and not the noun. The subject is Father/God, and “you” is the object and “will reward” is the verb. If “reward” was the noun then you would need another verb to allow it to be the object — i.e. “god will give you a reward.’ Do you see? But it says “your Father [...] will reward You.”

The word “reward,” as a noun, which doesn’t even come into use until the middle of the 14th c, btw, is “repayment for some service.”

As a verb the word “reward” implies: from before the 13c., from O.N.Fr. rewarder, variant of O.Fr. regarder “take notice of, regard, watch over,” from re-, intensive prefix, + garder “look, heed, watch.” So what Will God do [when you fast] ? What does God do when he "rewards" you: He will notice and watch over you. It is about relationship. Not a prize.