Exodus 40:20

20 He put also the witnessing, that is, the tables of the law, in the ark, and he set the bars within (the rings), and God's answering place above (the ark). (And he put the Witnessing, that is, the tablets of the Law, into the Ark, that is, the Box for the tablets, and he set the bars within the rings, and he put the propitiatory, that is, the mercy seat, or the lid, on the Box.)

Exodus 40:20 Meaning and Commentary

Exodus 40:20

And he took and put the testimony into the ark
The ten commands, called the "testimony", because they testified and declared what was the will of God with respect to things to be done, or not done. The Targum of Jonathan says, he put the broken pieces of the tables into it; but what became of them, or were done with them, we nowhere read; and it does not appear that any other, but those that Moses hewed by the order of God, were put into the ark; see ( Deuteronomy 10:1-5 )

and set the staves on the ark;
that it might be ready to be carried whenever a remove was necessary:

and put the mercy seat above upon the ark;
together with the cherubim.

Exodus 40:20 In-Context

18 And Moses areared it, and he set (up) the boards, and bases, and bars, and he ordained [the] pillars;

19 and he stretched out the roof upon the tabernacle, and he put a covering above (it), as the Lord commanded. (and he stretched out the tent over the Tabernacle, and he put the coverings over the tent, as the Lord commanded.)

20 He put also the witnessing, that is, the tables of the law, in the ark, and he set the bars within (the rings), and God's answering place above (the ark). (And he put the Witnessing, that is, the tablets of the Law, into the Ark, that is, the Box for the tablets, and he set the bars within the rings, and he put the propitiatory, that is, the mercy seat, or the lid, on the Box.)

21 And when he had brought the ark into the tabernacle, he hanged a veil before it, that he should fulfill the commandment of the Lord. (And when he had brought the Ark into the Tabernacle, he hung up the Veil in front of it, as the Lord commanded him.)

22 He setted also the board in the tabernacle of witnessing, at the north coast, without the veil, (And he put the table in the Tabernacle of the Witnessing, on the north side of the Tabernacle, in front of the Veil,)