Resources and Review Tests for Nedarim 57
1. The גמרא says that when you make a fruit אסור on yourself, you cant eat it’s חילופין either. The ר"ן says to look at דף מ"ז where our משנה is discussed. The ר"ן explains that רמי בר חמא has a ספק there whether when you say פּירות אלו עלי you are אסור בחילפיהן on a דאורייתא level because you said אלו or is it an איסור דרבנן like by all איסורי הנאה that whenever something is אסור on you, you cant be מחליף it and if you do there is a קנס דרבנן. The רמב"ם in הלכות נדרים פרק ה' הלכה י"ג paskens that חילופּי איסור נדרים are אסור מן התורה and yet in הלכות מאכלות אסורות פרק י"ג הלכה ט"ו he says by regular איסורי הנאה that the חליפּין are מותר! Rabbi Sorscher suggests that the רמב"ם is going like the ריטב"א who explains the ספק of רמי בר חמא to be that if one gets הנאה from דמי איסור הנאה, perhaps its like getting הנאה from the איסור itself. By contrast, regular איסורי הנאה really has no value since no one can use it. The only exception is נדרים where it has value, just not to the מודר. Therefore, by נדרים the חליפּין are אסור מדאורייתא but by regular איסורי הנאה they are מותר.
2. The גמרא brings a question as to what is the הלכה if you pull a vegetable out of the ground during שמיטה and then replant it the next year and it continues to grow to the level that the amount that grew is larger than the fruit you had planted originally. Do we say that the גידולין are מבטל the עיקר or not? The ר"ן understands that the גמרא’s real question is not just whether the גידולין can be מבטל the עיקר or not. Rather there is a question as to whether the גידולין themselves are מותר. The reason why they would not be מותר is that they are just an outgrowth and extension of the original plant (similar to the concept of כל היוצא מן הטמא טמא). Furthermore, while the גמרא just says you need רוב, the truth is it is כל לאו דוקה and you need שישים or whatever the normal שיעור is. The רא"ש disagrees on both counts. First, the גידולין are 100% מותר. The only question is whether they have the ability to be מבטל the עיקר. The reason they might not be מבטל it is because it is not really a תערובות of two items in the classic sense but rather just more growing out of the original עיקר. Furthermore, the רא"ש holds that you only need a simple majority and don’t need שישים like by other איסורים. The חזון אי"ש in אבן העזר סימן קל"ו דף נ"ז: אות א׳ ו"ט explains that in our case in a sense it is easier to become בטל since the עיקר is considered to have become "נתחלף ומתחדש" and becomes a completely new fruit and not fully connected to its earlier self. Interestingly, the גמרא later says that if you plant חולין מתוקנין and they grow, you take מעשר off all of it, even off the עיקר that had previously had תרומה removed. The גמרא suggests that this is just a חומרא. The ראשונים ask why don’t you have a problem of taking מן הפּטור על החייב since the עיקר is really פּטור and the גידולין are really חייב? The רא"ש answers that its not an issue since the fruit is completely evenly distributed with old and new so whichever piece you take the פּטור goes on the פּטור and the חייב goes on the חייב. This sounds like a bit of a סתירה to the previous רא"ש who said the fruit is not even a real תערובות.
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