Cross reference
Exodus 26:34
34 And thou shalt put the mercy seat upon the ark of the testimony in the most holy place.
Exodus 25:21
21 And thou shalt put the mercy seat above upon the ark; and in the ark thou shalt put the testimony that I shall give thee.
Exodus 40:20
20 And he took and put the testimony into the ark, and set the staves on the ark, and put the mercy seat above upon the ark:
Hebrews 9:5
5 And over it the cherubims of glory shadowing the mercyseat; of which we cannot now speak particularly.