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

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.