The Holy of Holies contained only the ark of the covenant, a wooden chest three feet, nine inches long; two feet, three inches wide; and two feet, three inches high. On the top of this chest was a beautiful “mercy seat” made of gold, with a cherub at each end. This was the throne of God in the tabernacle (Ex. 25:10-22, Ps 80:1, 99:1)
On the Day of Atonement, the blood was sprinkled on this mercy seat to cover the tablets of Law within the ark. God did not look at the broken Law, He saw the blood.
Warren Weirsbe, Bible Exposition Commentary New Testament, Volume 2, 1989, Cook Communications, Page 309