Exodus 25:16

25:16 You are to put into the ark the testimony ¹  that I will give to you.

Exodus 25:21

25:21 You are to put the atonement lid on top of the ark, and in the ark you are to put the testimony I am giving you.

Exodus 40:3

40:3 You are to place the ark of the testimony in it and shield the ark with the special curtain.

Exodus 40:20

40:20 He took the testimony and put it in the ark, attached the poles to the ark, and then put the atonement lid on the ark.

¹ sn The “testimony” is the Decalogue (Exod 24:12; 31:18; Deut 4:13; 9:9; 1 Kgs 8:9); the word identifies it as the witness or affirmation of God’s commandments belonging to his covenant with Israel. It expressed God’s will and man’s duty. In other cultures important documents were put at the feet of the gods in the temples.