Reference for Gittin 41:8

ואי אשמעינן חצר ה"א דוקא חצר אבל עבד ליגזר כפות אטו שאינו כפות קמ"ל

And again, if he had stated only the rule about a courtyard, I should have said that this applies strictly to a courtyard, but in the case of a slave I should debar one who is bound so as not to set a precedent for one who is not bound. Now I know [that this is not so].

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