In His first illustration of people practicing their righteousness to be seen of men, Jesus talks about giving to the poor (Matthew 6:2-4). He describes both the correct and incorrect motive for showing mercy upon another individual.
Describing the incorrect motive first, Jesus says, “Do not sound a trumpet before you.” Those with the incorrect motive do their giving “in the synagogue and in the streets.” These outward actions are covering up the unseen reason for doing this – “to be honored by men” – thereby receiving “their reward in full.” Jesus uses a very strong, negative word (according to the people of His day and ours as well) to describe a person with the wrong motive. He says they are “hypocrites.”