Exodus 40:20
Moses took the Testimony and placed it in the ark, attaching the poles to the ark; and he set the mercy seat atop the ark.
Berean Standard Bible
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:
He took and put the covenant into the ark, and set the poles on the ark, and put the mercy seat above on the ark.