BT Šab 47b(6) :נהי דליכ׳ א^י^סורא דאוריתא איסורא דרבנן מיהא איכא‏ : granted that the prohibition is not from the Torah, it is at least a rabbinic prohibition
See the entire entry for mihā; miḥḥaṯ adv. at least, in any case