Musar su Proverbi 14:10

In most cases, even at a mitzvah feast, if no words of Torah are spoken and there are no poor people present, quarreling and strife break out. For what pleasure does the Holy One, Blessed is He, derive from an affair of eating and drinking that is devoid of the rejoicing of a mitzvah? And how much more so if the rejoicing is mixed with thoughts of sin, for instance, when men and women, and teenage boys and girls sit together! Great pitfalls are thus created. Men and women dance in circles together, not realizing that the Satan, with many demons are dancing in front of them. What is the value of such rejoicing? Yet this iniquity has become very common, on account of our many sins, throughout the lands of Poland and Lithuania. Therefore let every man who fears the word of Hashem be careful to seat the men and women separately in order to distance himself from transgression and in order that the Satan will not mix up the joy of the mitzvah. For it is stated, “In our rejoicing let no stranger mix in” (Mishlei 14:10). [The “stranger” is the Satan, as it is stated, “Do not bow down to a strange god” — Shemos 34:14 — again referring to the Satan.] And let him be sure to grant a portion of every feast to the poor [as I have discussed at length in Chapter Ten].