The Shitta Mekubetzes on Nedarim (8a) quotes the רא"ם.
Who does this refer to?
(My guesses for possible candidates are R. Eliezer of Metz, R. Eliyahu Mizrachi, and Ri Ibn Migash.)
Extra points to anyone who can locate the source.
It must be R. Eliezer of Metz, as Tosafos there s.v. mushba quote "R. Eliezer".