Read Numbers 16:40 Using Other Translations
To be a memorial unto the children of Israel, that no stranger, which is not of the seed of Aaron, come near to offer incense before the LORD; that he be not as Korah, and as his company: as the LORD said to him by the hand of Moses.
to be a reminder to the people of Israel, so that no outsider, who is not of the descendants of Aaron, should draw near to burn incense before the LORD, lest he become like Korah and his company--as the LORD said to him through Moses.
This would warn the Israelites that no unauthorized person—no one who was not a descendant of Aaron—should ever enter the LORD ’s presence to burn incense. If anyone did, the same thing would happen to him as happened to Korah and his followers. So the LORD ’s instructions to Moses were carried out.