Germane to this weeks parsha and the daf yomi masechta...
The Mishna in Nedarim [16b] says that a שבועה one makes not to fulfill a mitzva is not valid while a neder one makes not to fulfill a mitzva is valid. So if a person made a שבועה not to sit in a succah - he is permitted to sit in a succah while if he made neder forbidding himself to sit in a succah - he may not sit in the succah. The gemara derives this from psukim.
Asked the Nimmukei Yosef [and the Ritva, Sefer Hachinuch and others] : Why don't we allow the person to fulfill his neder on the mitzva because of the rule the עשה [the mitzva he swore not to do] is דוחה לא תעשה [the איסור נדר].
He answers that it is not possible to fulfill a mitzva with a קונם - an איסור הנאה, because the Torah does not want a person to fulfill mitzvos with items that are אסור בהנאה.
He further answers that נדרים have not only an עשה but a לא תעשה as well [as he shows from the psukim] and an עשה is not דוחה a לא תעשה ועשה.
I was bothered: What is the question of the rishonim?? We have a pasuk that teaches us that a neder is חל on a דבר מצוה so how can they ask the question that the עשה should be דוחה the לא תעשה of neder. The pasuk says otherwise and if we have a pasuk, that is a "sof pasuk" end of story?!!
Explains the Shaar Hamelech [Nedarim 6/3]: What the N"Y [and other rishonim] meant was that we should derive from here that we should derive from here a rule - an עשה is not דוחה a לא תעשה.
Aaaa-hhhaah!
And the answer is that such a rule may not be derived because here is an עשה and לא תעשה so it is a different story and of course the עשה is not דוחה [I don't know how the first answer fits with the question].
But that presents noch a kashya - a different question. The עשה of nedarim can be uprooted by going to a חכם and doing שאלה thereby uprooting the neder. So let us derive from here that even when one can be שואל we nevertheless rule that an עשה is not דוחה a לא תעשה ועשה. For here one can uproot the לא תעשה and עשה and yet we tell him not to do the עשה to override the לא תעשה and עשה.
Great.
But it's not true. The gemara in Yevamos [5a] teaches that the עשה of מצורע IS דוחה the לא תעשה ועשה of nazir because the latter can be uprooted.
Uh oh.
Answers the Shaar Hemelech that everything is cool [my words not his...]. The fact that the עשה of מצורע is דוחה the לא תעשה ועשה of nazir [because you can do שאלה on the נזירות] is derived from a special pasuk and thus cannot be a model for other cases.
Let us take this a step further, if you will.
It emerges according to the Shaar Hamelech that we derive from the gemara in Yevamos from a pasuk that with respect to a nazir an עשה IS דוחה a לא תעשה ועשה when שאלה is an option. We learn from a pasuk in the gemara in Nedarim that with respect to nedarim an עשה is NOT דוחה a לא תעשה ועשה when שאלה is an option.
So which one is it?
מודנה ["strange" in Latin].
The plot thickens!!
To be continued אי"ה and בלי נדר!
לזכות ידידי אהובי ר' צבי משה בן שרה לאה לברכה והצלחה וכל טוב סלה
ולזכות ידידי אהובי ר' ברוך בן ר' משה לברכה והצלחה וכל טוב סלה
ולרפואת אברהם זלמן בן ברכה בתוך שח"י