"When you fast, put oil on your head ... so that it will not be obvious ... that you are fasting." Matt. 6:17-18
In Jesus' day the Jews put ashes on their heads when they were fasting, as a sign to others of their devotion to God. Jesus was concerned that people were fasting only for the sake of showing it to the people around them. He warned that if people performed religious acts to impress others, they could be sure they were not impressing God. If they were looking merely for esteem from others, said Jesus, they had already "received their reward in full."
The word "reward" here is a business term referring to complete payment. In Jesus' day, if you made full payment for something you bought, the owner would write on the receipt the word used here for "reward," meaning "paid in full." So when Jesus says that if you pray to be noticed by others, or if you give something to show your generosity to others, or if you fast so as to show others how godly you are, then you may get the applause of people, but that's all you get. That's your payment in full, and there will be no reward from God.
It's clear that we cannot use fasting as a way to impress God and earn his favor. But it's also clear that fasting and prayer are often cited together in Scripture to describe necessary spiritual disciplines. Jesus says, "When you fast ..." assuming that you will fast. I personally have something to learn here.
For many of us, Lord, fasting is not part of our spiritual discipline. Teach us that in fasting we are reminded to focus on you and be content in you. In Jesus' name, Amen.
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