Reference for Pesachim 175:16

א"ל עינא סבא ואמרי לה פתיא אוכמא מיני ומינך תסתיים שמעתתא מתניתין בדקפדי אהדדי ברייתא דלא קפדי אהדדי:

Yet surely the first clause teaches: 'Nor on behalf of his wife [etc.] save with their consent': hence if nothing is said, she cannot discharge [her obligation thus]? - What does 'save with their consent' mean? Not that they said 'yes,' but when they said nothing, which excludes [the case] where they said 'no.'

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