Jamieson, Fausset and Brown on 2 Chronicles 26:16-21

16-21. he transgressed against the Lord, &c.--(See on 2Ki 15:5). This daring and wicked act is in both records traced to the intoxicating influence of overweening pride and vanity. But here the additional circumstances are stated, that his entrance was opposed, and strong remonstrances made (1Ch 6:10) by the high priest, who was accompanied by eighty inferior priests. Rage and threats were the only answers he deigned to return, but God took care to vindicate the sacredness of the priestly office. At the moment the king lifted the censer, He struck him with leprosy. The earthquake mentioned (Am 1:1) is said to have been felt at the moment [Josephus].