Exodus 37:6 KJV
And he made the mercy seat of pure gold: two cubits and a half was the length thereof, and one cubit and a half the breadth thereof.
Exodus 37:6, King James Version
In context
5 And he put the staves into the rings by the sides of the ark, to bear the ark.
6 And he made the mercy seat of pure gold: two cubits and a half was the length thereof, and one cubit and a half the breadth thereof.
7 And he made two cherubims of gold, beaten out of one piece made he them, on the two ends of the mercy seat;