And Azariah the priest went in after him, and with him fourscore priests of the LORD, that were valiant men:

Matthew Henry's Concise Commentary

26:16-23 The transgression of the kings before Uzziah was, forsaking the temple of the Lord, and burning incense upon idolatrous altars. But his transgression was, going into the holy place, and attempting to burn incense upon the altar of God. See how hard it is to avoid one extreme, and not run into another. Pride of heart was at the bottom of his sin; a lust that ruins many. Instead of lifting up the name God in gratitude to him who had done so much for him, his heart was lifted up to his hurt. Men's pretending to forbidden knowledge, and seeking things too high for them, are owing to pride of heart. The incense of our prayers must be, by faith, put into the hands of our Lord Jesus, the great High Priest of our profession, else we cannot expect it to be accepted by God, Re 8:3. Though Uzziah strove with the priests, he would not strive with his Maker. But he was punished for his transgression; he continued a leper to his death, shut out from society. The punishment answered the sin as face to face in a glass. Pride was at the bottom of his transgression, and thus God humbled him, and put dishonour upon him. Those that covet forbidden honours, forfeit allowed ones. Adam, by catching at the tree of knowledge which he might not eat of, debarred himself of the tree of life which he might have eaten of. Let all that read say, The Lord is righteous. And when the Lord sees good to throw prosperous and useful men aside, as broken vessels, if he raises up others to fill their places, they may rejoice to renounce all worldly concerns, and employ their remaining days in preparation for death.