Kommentar zu Jechezkiel 42:9

And below these chambers I do not know whether this comes to teach that they had tunnels beneath them, or whether it comes to teach that there were chambers in the east of the Court, and [that] since the mountain slopes [downward] to the east, he calls it “and below these chambers.” And he is saying this: And at the lowest point of the Court, to the approach that was on the east as one comes to them from the outer Court.