Ezekiel 43:16-18 Common English Bible (CEB)
16 The hearth is twenty-one feet square; each side is equal to the others. 17 The ledge around the hearth is twenty-four and a half feet long by twenty-four and a half feet wide, a square. Its outer rim is ten and a half inches, and its base all around is twenty-one inches. Its ramp faces east.
Purification of the altar
18 He said to me, Human one, the Lord God proclaims: These are the regulations established for the altar on the day when it is prepared for making entirely burned offerings and dashing blood on it.