Giving, praying, fasting - these were important acts of piety for God's people in Christ's day and for us today. But Christ goes to the heart of the matter:  why do you do these holy exercises, and for whom are you doing them? Christ warns us to not put on a display for others to gain their approval. Don't do your acts of piety to gain glory for yourself, but seek God's glory and he will reward you in due season.