Why was Ozias expelled from the temple after entering with incense?

Following the death of Amasias, all the people of Juda took his sixteen-year-old son Ozias and made him king in place of his father; he reigned for fifty-two years in Jerusalem, and the name of his mother was Jechelia of Jerusalem. He built Ailath and restored it to the dominion of Juda. Ozias did that which was right in the eyes of the Lord according to all that his father had done, seeking God in the days of Zacharias, who understood and saw God; and as long as he sought the Lord, God directed him in all things.

He marched out to battle against the Philistines, demolishing the wall of Geth, the wall of Jabnia, and the wall of Azotus, and built towns in the territory of Azotus and among the Philistines. God helped him against the Philistines, against the Arabians who dwelt in Gurbaal, and against the Ammonites, who gave gifts to Ozias; and his name spread abroad even to the entrance of Egypt because of his frequent victories. Ozias constructed fortified towers in Jerusalem at the Corner Gate, at the Valley Gate, and on the turning of the wall, strengthening them. He also built towers in the wilderness and dug numerous cisterns because he possessed much cattle both in the plains and in the waste of the desert, and he maintained husbandmen and vinedressers in the mountains and in Carmel, for he was a man devoted to husbandry. His army of fighting men went out to battle under the hand of Jehiel the scribe, Maasias the doctor, and Henanias, one of the king's captains. The number of chiefs of families was two thousand six hundred valiant men, under whose command served three hundred and seven thousand five hundred combat troops fit for war. Ozias provided this army with shields, spears, helmets, coats of mail, bows, and slings to cast stones. Furthermore, he made in Jerusalem engines of diverse kinds placed on the towers and at the corners of the walls to shoot arrows and great stones, and his fame spread far abroad because the Lord helped him and strengthened him.

When he was made strong, his heart was lifted up to his own destruction, and he neglected the Lord his God. He entered the temple of the Lord to burn incense upon the altar of incense. Immediately High Priest Azarias went in after him, accompanied by eighty valiant priests of the Lord. Standing before the king, they said: 'It doth not belong to thee, Ozias, to burn incense to the Lord, but to the priests, that is, to the sons of Aaron, who are consecrated for this ministry: go out of the sanctuary, do not despise: for this thing shall not be accounted to thy glory by the Lord God.' Ozias became enraged, and holding in his hand the censer to burn incense, threatened the priests. Presently leprosy broke out upon his forehead before the priests in the house of the Lord at the altar of incense.

When High Priest Azarias and all the priests looked upon him and saw the leprosy on his forehead, they hastened to expel him from the sanctuary; the king himself also trembled to depart because he felt the stroke of the Lord. Ozias the king remained a leper until the day of his death, dwelling in a house apart because he was cast out from the house of the Lord, while his son Joatham governed the king's house and judged the people of the land. The rest of the acts of Ozias, from first to last, were written by the prophet Isaias the son of Amos. When Ozias died, he was buried with his ancestors in the field of the royal sepulchres because he was a leper, and Joatham his son reigned in his stead.