16 “When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show others they are fasting. Truly I tell you, they have received their reward in full. 17 But when you fast, put oil on your head and wash your face, 18 so that it will not be obvious to others that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you.
I realized when reading this that I've heard very few sermons (if any) on fasting. Notice how Jesus says when you fast, not if you fast. Fasting is a good thing, but we need to know the right way to do it.
Physically, it must be safe to fast - this isn't possible for everyone.
But, more importantly, we need to fast correctly from a spiritual perspective.
We can't fast in order to receive praise from men. We can't fast in order to try to be seen as being holy or super-spiritual.
That said, if someone notices that we are fasting, we haven't not lost all spiritual benefit of the fast. As John Piper says in this article.....
If someone finds out you are fasting, you haven't sinned. The value of your fast is not destroyed if someone notices that you have skipped lunch. It is possible to fast with other people—for example: our staff fasting together on a planning retreat to seek the Lord—it is possible to fast like that and NOT to fast "to be seen by men." Being and are not the same. Being seen fasting is a mere external event. Fasting TO BE SEEN is a self-exalting motive of the heart.
So, what is the reward of fasting?
the best place to find out the reward of our fasting is to look here in the Sermon on the Mount. For example, the prayer that Jesus just taught us to pray in Matthew 6:9–13 begins with three main longings: that God's name be hallowed or revered, that his kingdom come, that his will be done on earth the way it's done in heaven. That is the main reward God gives for our fasting. We fast out of longing for God's name to be known and cherished and honored, and longing for his rule to be extended and then consummated in history, and longing for his will to hold sway everywhere ...
Tomorrow's Bible In a Year Passage: Isaiah 34-36, Matthew 6:19-34