Exodus 25:22
And there I will meet with you, and I will commune with you from above the mercy seat, from between the two cherubim which are on the ark of the testimony, of all things which I will give you in commandment to the children of Israel.
Torrey's Topical Textbook—AKJV

Leviticus 16:2
And the LORD said to Moses, Speak to Aaron your brother, that he come not at all times into the holy place within the veil before the mercy seat, which is on the ark; that he die not: for I will appear in the cloud on the mercy seat.
Torrey's Topical Textbook—AKJV