While researching for the above write-up, I came across an interesting Teshuvah from the Divrei Malkiel (4:86), one of the leading Litvishe poskim of the late nineteenth and early twentieth centuries. The question was sent to him from the rav of Bucharest, Rumania, deploring the progressive attitudes towards shemiras mitzvos that existed among many wealthier members of his community. One issue was that they would postpone a bris milah from the eighth day to a secular legal holiday, to make it easier for people to attend. The Divrei Malkiel found this practice extremely abhorrent – the seudas bris is to celebrate that a mitzvah involving mesiras nefesh was observed to its fullest. By postponing the bris to accommodate the seudah, the baalei simcha are inverting the importance — making, quite literally, the tafeil into the ikar and the ikar into the tafeil. The Divrei Malkiel suggests that, under these circumstances, there would be no mitzvah accomplished with the bris seudah. Since the entire bris was delayed against halachah, it now becomes the celebration of an aveirah – the non-fulfillment of a bris on the eighth day, rather than the celebration of a mitzvah!
The Divrei Malkiel notes that this not only confuses the ikar (performing the bris at the first opportunity, and the mitzvah of performing it on the eighth day) with the tafeil (the seudah celebration), but that, if indeed the bris was delayed because of convenience, there is no mitzvah of having a celebratory meal. His rationale is simple: The purpose of the celebratory meal is to demonstrate our scrupulous observance of this mitzvah that involves sacrifice. But, in this instance, it is a declaration that the father did not want to perform the mitzvah properly. Therefore, any celebration becomes a farce and is not a simchas mitzvah!
The exact question asked of the Divrei Malkiel was asked many hundreds of years ago of the Tashbaz (3:8), who ruled the same way. The case in this instance was that the eighth day after the birth fell on Sunday, the tenth of Av – in other words, Tisha B’Av nidche, the day that the ninth of Av is observed in practice. The family wanted to push off the bris to Monday in order to have it on a day when there would be a seudah. Similar to the Divrei Malkiel, the Tashbatz writes that pushing off the bris to accommodate a more convenient seudah confuses the ikar with the tafeil and is sinful, for it violates performing the bris on the eighth day. He concludes, similarly to the Divrei Malkiel, that in this situation there is no mitzvah to have a seudah.
