Exodus 25:15

And thou shalt make staves of shittim wood, and overlay them with gold.

And thou shalt put the staves into the rings by the sides of the ark, that the ark may be borne with them.

And thou shalt put into the ark the testimony which I shall give thee.

And thou shalt make a mercy seat of pure gold: two cubits and a half shall be the length thereof, and a cubit and a half the breadth thereof.