Midrasz do Diwrej ha-jamim II 26:17

9) R. Shimon b. Elazar says: Plague-spots come also because of pride. For thus do we find with Uzziyahu (king of Judah), viz. (II Chronicles 26:16) "But when he grew strong, his heart grew proud to (the point of) corruption. And he rebelled against the L–rd his G d, and he came into the sanctuary of the L–rd to burn incense on the incense altar (II Chronicles 26:17) And there after him Azaryahu the Cohein and with him Cohanim of the L–rd, eighty strong (II Chronicles 26:18) And they stood over Uzziyahu the king, and they said to him: 'It is not for you, Uzziyahu, to burn incense to the L–rd, but for the Cohanim, the sons of Aaron who are consecrated for the burning of incense. Leave the sanctuary …' And Uzziyahu fumed, and in his hand …" (and he was stricken with leprosy.)