Cross reference
Exodus 26:34
34 You are to put the cover on the ark of the law, inside the most holy place.
Exodus 25:21
21 And put the cover over the ark, and in the ark the record which I will give you.
Exodus 40:20
20 And he took the law and put it inside the ark, and put the rods at its side and the cover over it;
Hebrews 9:5
5 And over it were the winged ones of glory with their wings covering the mercy-seat; about which it is not possible now to say anything in detail.