'Mercy seat' in the Bible

The Lord said to Moses: “Tell your brother Aaron that he may not come whenever he wants into the holy place behind the veil in front of the mercy seat on the ark or else he will die, because I appear in the cloud above the mercy seat.

He is to put the incense on the fire before the Lord, so that the cloud of incense covers the mercy seat that is over the testimony, or else he will die.

He is to take some of the bull’s blood and sprinkle it with his finger against the east side of the mercy seat; then he will sprinkle some of the blood with his finger before the mercy seat seven times.

“When he slaughters the male goat for the people’s sin offering and brings its blood inside the veil, he must do the same with its blood as he did with the bull’s blood: he is to sprinkle it against the mercy seat and in front of it.