Hebrews 10:19-20

Having therefore, brethren, confidence to enter the holiest by the blood of Jesus,

Revelation 11:19

And the temple of God was opened in heaven, and there was seen in his temple, the ark of the covenant of the Lord; and there were lightnings and voices and thunderings, and an earthquake, and great 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
Having therefore, brethren, confidence to enter the holiest by the blood of Jesus,
Revelation 11:19
And the temple of God was opened in heaven, and there was seen in his temple, the ark of the covenant of the Lord; and there were lightnings and voices and thunderings, and an earthquake, and great hail.