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.

[25:16]  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.