Ezekiel 43:26 in the World English Bible
Seven days shall they make atonement for the altar and purify it. So shall they consecrate it.
Context
25 Seven days shalt thou prepare every day a goat for a sin offering: they shall also prepare a young bullock, and a ram out of the flock, without blemish.
26 Seven days shall they purge the altar and purify it; and they shall consecrate themselves.
27 And when these days are expired, it shall be, that upon the eighth day, and so forward, the priests shall make your burnt offerings upon the altar, and your peace offerings; and I will accept you, saith the Lord GOD.