Numbers 18:4
They shall join you and keep guard over the tent of meeting for all the service of the tent, and no outsider shall come near you.
Numbers 1:51
When the tabernacle is to set out, the Levites shall take it down, and when the tabernacle is to be pitched, the Levites shall set it up. And if any outsider comes near, he shall be put to death.
Numbers 3:10
And you shall appoint Aaron and his sons, and they shall guard their priesthood. But if any outsider comes near, he shall be put to death."
1 Samuel 6:19
And he struck some of the men of Beth-shemesh, because they looked upon the ark of the LORD. He struck seventy men of them, and the people mourned because the LORD had struck the people with a great blow.
2 Samuel 6:6-7
And when they came to the threshing floor of Nacon, Uzzah put out his hand to the ark of God and took hold of it, for the oxen stumbled.