Ezekiel 43:16-18 New Revised Standard Version (NRSV)
16 The altar hearth shall be square, twelve cubits long by twelve wide. 17 The ledge also shall be square, fourteen cubits long by fourteen wide, with a rim around it half a cubit wide, and its surrounding base, one cubit. Its steps shall face east.
18 Then he said to me: Mortal, thus says the Lord God: These are the ordinances for the altar: On the day when it is erected for offering burnt offerings upon it and for dashing blood against it,