2 “So when you give to the needy, do not announce it with trumpets, as the hypocrites do in the synagogues and on the streets, to be honored by others. Truly I tell you, they have received their reward in full. 3 But when you give to the needy, do not let your left hand know what your right hand is doing, 4 so that your giving may be in secret. Then your Father, who sees what is done in secret, will reward you.
Jesus speaks here of acts of mercy to help the needy. For Christians it is an action taken in thanksgiving to Jesus for all that he has done for us in his life, death, and resurrection. We are wholly blessed, and we show love by helping others. These are actions of combined love to God and to others.
It is no surprise that Jesus tells us that we should not act to draw attention to ourselves. Quite clearly it is not all about us, but the focus is on an action of self-forgetful love. The hypocrites may act for the praise of their generosity, and they will receive that paltry reward. Those who belong to Jesus are expressing delight in being forgiven and having blessed, eternal life and want the Lord to know they love him. That is and end in itself. The reward is a deeper sense of communion with our God. Acting so that only you and the Lord know what you have done is infinitely better than the grudging acknowledgement by others that we are generous.
When we find our hearts are cold to God and yearning for the praise of the world, we need to reflect on all that we have in Christ so that we are warmed to the desire to love as we are loved.