Yosef Karo, Translation:Shulchan Aruch — Orach Chaim 352…
“ If it reached the bottom ten tefachim and the wall is slanted such that the scroll can rest on it, it is forbidden to roll it back; so that it is not mistreated, he should turn it around onto the text. If the wall is not slanted, as long as it has not reached the ground, he may roll it back. ”
