Hezekiah's reforms in 2 Chronicles 29-30
2 things strike me, from this passage:
1. The priests were behind the curve in revival of Yahweh worship, when they should have been leading the charge.
2. God favored their actions, even though they were technically against the law (all worshiping the second month, when some were still unclean). Without the clear approval of God, many would condemn this kind of thing absolutely. But God calls us to perfection, without being a perfectionist.