Exodus 25:21

You shall put the mercy seat on the top of the ark, and in the ark you shall put the Testimony which I will give you.

Exodus 26:34

You shall put the mercy seat on the ark of the Testimony in the Holy of Holies.

Exodus 25:16-17

You shall put into the ark the Testimony (Ten Commandments) which I will give you.

Romans 10:4

For Christ is the end of the law [it leads to Him and its purpose is fulfilled in Him], for [granting] righteousness to everyone who believes [in Him as Savior].

Treasury of Scripture Knowledge

Summary

And thou shalt put the mercy seat above upon the ark; and in the ark thou shalt put the testimony that I shall give thee.

Bible References

Mercy seat

Exodus 25:17
“You shall make a mercy seat (cover) of pure gold, two and a half cubits long and one and a half cubits wide.
Exodus 26:34
You shall put the mercy seat on the ark of the Testimony in the Holy of Holies.
Romans 10:4
For Christ is the end of the law [it leads to Him and its purpose is fulfilled in Him], for [granting] righteousness to everyone who believes [in Him as Savior].

In

Exodus 25:16
You shall put into the ark the Testimony (Ten Commandments) which I will give you.

General references

Exodus 16:34
As the Lord commanded Moses, so Aaron [eventually] placed it in the presence of the Testimony, to be kept.
Exodus 37:6
Bezalel made the mercy seat of pure gold; it was two and a half cubits long, and one and a half cubits wide.
Revelation 15:5
After these things I looked, and the temple (sanctuary) of the tabernacle of the testimony in heaven was opened,