משנה על שמות 30:18

The laver was between the porch and the altar, a little to the south. Between the porch and the altar there were twenty-two cubits. There were twelve steps there, each step being half a cubit high and a cubit broad. There was a cubit, a cubit and a level space of three cubits, then a cubit, a cubit and a level space of three cubits, then at the top a cubit, a cubit and a level space of four cubits. Rabbi Judah says that at the top there was a cubit, a cubit and a level space of five cubits.