Resources for Nedarim 15

1.     The גמרא says that if someone makes a נדר by saying הנאת תשמישך עלי the נדר is חל but if he just made a נדר to not have תשמיש with his wife it would not be חל because his is משועבד to her. The ר"ן and רשב"א ask why there would be an איסור for him to be משמש with her even if he said הנאת תשמישך עלי—after all, he has a מצות עונה to be with her. If so, we should apply the principle of מצוות לאו ליהנות ניתנו and say that any הנאה he gets would not be considered a הנאה! The ר"ן answers that מצוות לאו ליהנות ניתנו just means that the עצם קיום המצוה is not considered a הנאה. However, a הנאת הגוף is certainly considered a הנאה. The proof to this is that the גמרא in ר"ה says that if someone is מודר הנאה ממעין they can dunk in it for טבילה purposes since it is a מצוה but only in the winter when they won’t enjoy it. We see from there that even though it is a טבילה של מצוה it would be forbidden in the summer since the person would get a הנאת הגוף from it. The רשב"א disagrees and says that the מצוה of עונה is only if he has a שעבוד to her, and since the נדר gets rid of the שעבוד, there is no מצוה to speak of. As to the general מצוה of פּרו ורבו, that would not be a היתר since he can be with someone else. We see two things from this רשב"א: 1) since he does not say what the ר"ן says it must be that he holds that even a הנאת הגוף would be permitted in a case of a מצוה. 2) the הנאה  is only permitted if there is no other way to do the מצוה. The אבני מילואים in סימן כ"ח אות ס discusses this רשב"א and asks that the גמרא in ר"ה says that if you are מודר הנאה from someone that person can still blow שופר for you on ר"ה since מצוות לאו ליהנות נתנו. The אבני מילואים asks why doesn’t the גמרא say that the מדיר should ask someone who he is not מודר הנאה from to blow for him? He answers that there are two distinct levels of מצוות לאו ליהנות נתנו. The first level is the עצם הנאה of the קיום מצוה. This is not considered a הנאה at all and there is no need to avoid it even if one could. Everyone agrees to this. The second level is getting a הנאת הגוף. This is only מותר if there is no other way to do the מצוה. The מה͏ר"ץ חיות explains the סברא as follows: the היתר of מצוות לאו ליהות נתנו is based on the concept that the person is really trying to do the מצוה and the side הנאת הגוף is not something he is being מכוון for. (As to the issue of פּסיק רישא , the ר"ן in חולין דף צ"ג  says that there is no איסור of getting benefit from איסורי הנאה  if there is no כוונה.) However, if he has another way to do it without getting הנאה  from the איסור and yet does not pursue it that shows that he is מכוון for the איסור. As to the proof of the ר"ן from the גמרא in ר"ה about bathing in the summer, the      מה͏ר"ץ חיות  brings from the שער המלך that the מאירי says that there is no היתר there of מצוות לאו ליהנות נתנו since the person will still get הנאה from the מעין in the summer after the טבילה is over as he is now cooled off. The ר"ן would presumably say back to that that since he had to dunk in the מעין for the מצוה, the later הנאה would still be part of the מצוה. Another question on the רשב"א is the גמרא at the beginning of יבמות that says we learn עשה דוחה לא תעשה from כלאים בציצית. According to the רשב"א there is no דחיית הלאו at all in that case since מצוות לאו ליהנות נתנו so the הנאה he gets from wearing of the the ציצית של כלאים shouldn’t be considered הנאה של איסור! The בית הלוי answers that it is not the הנאה that is the לאו but rather the לבישה. The need for הנאה that the גמרא discusses is just a סימן as to whether it is a לבישה שיש בו הנאה but it is not the סיבת האיסור.

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