Yosef Karo, Translation:Shulchan Aruch — Orach Chaim 667…
“ If Shabbat falls on the evening after the last day of the holiday, the custom is to not use the decorations until after Shabbat. There are those who are permissive. Rem"a: There are some who have the custom upon leaving the sukkah of saying "May it be Your will that we merit to sit in the Leviathan's sukkah" (Kol Bo) . ”
