Our Lord was the “prince of peace” (Isa. 9.6; Eph. 2.14); but that does not mean he refrained from denouncing the sins of his contemporaries — severely.
In fact, Jesus repeatedly scolded the religious leaders of his day (cf. Mt. 23.1ff). One such indictment against them concerned their hypocrisy. Sure, they did charity; they prayed to God; they fasted (Mt. 6.1-18). But they did such things purely to receive the praise and admiration of the public (Mt. 6.1-2, 5, 16).
In response, the Lord said: “They have their reward” (Mt. 6.2, 5, 16). What did he mean by this?
The word, "have," in the original language, is not the usual word designating that concept. Instead, apecho, is a compound form, literally meaning: to have away from. The term conveys the idea of a trade-off — to receive one thing by letting go of another; to gain something by being far away from something else. Thus, this statement would be better rendered: “they are trading away their reward.”
His point is this: if they sought the admiration of the public for their charity, praying, and fasting, then they are certainly receiving it. But, in exchange, they are trading away the admiration of God! They may have the temporary praise of men, but they are far away from the eternal praise of heaven. What a foolhardy endeavor!
Conversely, the Lord instructs us to seek God’s praise, by doing charity, praying, and fasting without seeking public acknowledgment, and we shall be doubly rewarded — in private and in public (Mt. 6.4, 6, 18). Regardless of how others view us, his perception is the one that matters the most (cf. Jn. 5.44; Rm. 2.29).