Exodus 37:1-3

Then Bezalel made the ark of acacia wood; two and a half cubits was its length, a cubit and a half its width, and a cubit and a half its height. He overlaid it with pure gold inside and outside, and made a molding of gold all around it. And he cast for it four rings of gold to be set in its four corners: two rings on one side, and two rings on the other side of it.