Reference for Nedarim 55:1

חוץ מבשבועה ובית הלל אומרים אף בשבועה

EXCEPTING THAT SUSTAINED BY AN OATH;<span class="x" onmousemove="('comment',' I.e. one may not vow, 'may this corn be forbidden me by an oath if' etc. ');">¹</span>

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