Hebrews 10:19-20

Since then, brethren, we have free access to the Holy place through the blood of Jesus,

Revelation 11:19

Then the doors of God's sanctuary in Heaven were opened, and the Ark, in which His Covenant was, was seen in His sanctuary; and there came flashes of lightning, and voices, and peals of thunder, and an earthquake, and heavy hail.

Treasury of Scripture Knowledge

Summary

But they shall not go in to see when the holy things are covered, lest they die.

Bible References

They shall

Hebrews 10:19
Since then, brethren, we have free access to the Holy place through the blood of Jesus,
Revelation 11:19
Then the doors of God's sanctuary in Heaven were opened, and the Ark, in which His Covenant was, was seen in His sanctuary; and there came flashes of lightning, and voices, and peals of thunder, and an earthquake, and heavy hail.