Exodus 16:34

16:34 Just as the Lord commanded Moses, so Aaron placed it before the Testimony for safekeeping.

Exodus 25:16

25:16 You are to put into the ark the testimony 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.