'Unfaithfully' in the Bible

But when he became strong, he grew arrogant and it led to his own destruction. He acted unfaithfully against the Lord his God by going into the Lord’s sanctuary to burn incense on the incense altar.

They took their stand against King Uzziah and said, “Uzziah, you have no right to offer incense to the Lord—only the consecrated priests, the descendants of Aaron, have the right to offer incense. Leave the sanctuary, for you have acted unfaithfully! You will not receive honor from the Lord God.”