Exodus 25:15-16

25:15 The poles must remain in the rings of the ark; they must not be removed from it. 25:16 You are to put into the ark the testimony ¹  that I will give to you.

Exodus 26:34

26:34 You are to put the atonement lid on the ark of the testimony in the Most Holy Place.

Exodus 30:26

30:26 “With it you are to anoint the tent of meeting, the ark of the testimony,

Exodus 39:35

39:35 the ark of the testimony and its poles, and the atonement lid;

[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.