“But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret. Then your Father, who sees what is done in secret, will reward you”

Jesus is saying that if your motive for giving is to draw attention to yourself, then you are trading an eternal reward for a temporal one. It is not as important whether others know about your giving. It is important, however, to examine the motives behind why you made your giving known to others.