2 Chronicles 26:16
But when he was strong, his heart was lifted up to his destruction: for he transgressed against the LORD his God, and went into the temple of the LORD to burn incense upon the altar of incense. But when he was strong, his heart was lifted up to his destruction: for he transgressed against the LORD his God, and went into the temple of the LORD to burn incense upon the altar of incense.
When he became strong, his strength and prosperity lifted up his heart in pride, and that pride led through unfaithfulness and disobedience to his ruin and destruction. His growing strength turned him to pride that brought his ruin through unfaithfulness, with success and exalted position fostering the pride that led to his destruction. His transgression was presumption in violating God's plain command and order by entering the temple sanctuary to burn incense upon the altar. That was a priestly office reserved for the descendants of Aaron alone to officiate as priests, which he was not authorized to perform.
His reign had outward prosperity without matching spiritual growth, with temple worship continuing and crowds still gathering while pride and formality replaced humility and sincerity. He could have used his instruction and example to lead his people to reverence God and honor the sacred temple services, but instead his power lifted his heart into disobedience. Azariah the high priest and his associates withstood him, remonstrated with him and pleaded with him to turn from his purpose, telling him he had trespassed and that it would not be for his honor.
His refusal to turn back when rebuked brought God's punishment and divine judgment, and he became a leper. As a leper he had to give up the throne and withdraw from society, showing that royal rank did not exempt him from the consequences of the disease. Neither high position nor a long record of service excuses violating a plain command of God. Success does not qualify people to take up work God has not assigned them.