After the building of the tabernacle was completed, Moses examined all the work, and compared it with the pattern, and directions he had received of God, and he saw that every part of it agreed with the pattern; and he blessed the people. SR 153.2
God gave a pattern of the ark to Moses, with special directions how to make it. The ark was made to contain the tables of stone, on which God engraved, with His own finger, the Ten Commandments. It was in form like a chest, and was overlaid and inlaid with pure gold. It was ornamented with crowns of gold round about the top. The cover of this sacred chest was the mercy seat, made of solid gold. On each end of the mercy seat was fixed a cherub of pure, solid gold. Their faces were turned toward each other and were looking reverentially downward toward the mercy seat, which represented all the heavenly angels looking with interest and reverence upon the law of God deposited in the ark in the heavenly sanctuary. These cherubs had wings. One wing of each angel was stretched forth on high, while the other wing of each angel covered his form. The ark of the earthly sanctuary was the pattern of the true ark in heaven. There, beside the heavenly ark, stand living angels, at either end of the ark, each with one wing overshadowing the mercy seat, and stretching forth on high, while the other wings are folded over their forms in token of reverence and humility. SR 153.3
In the earthly ark Moses was required to place the tables of stone. These were called the tables of the testimony; and the ark was called the ark of the testimony, because they contained God's testimony in the Ten Commandments. SR 154.1