Numbers 16:39-40

So Eleazar the priest took the bronze censers, which those who were burned up had presented, and they were hammered out as a covering on the altar, to be a memorial to the children of Israel that no outsider, who is not a descendant of Aaron, should come near to offer incense before the LORD, that he might not become like Korah and his companions, just as the LORD had said to him through Moses.