NUM207 When it comes to argument, the Mishnah (Avot 5:17) makes it clear which type is sanctioned and is "Jewish" and which type of argument undermines the peace. The argument or rebellion of Korach who challenged the authority of Moses in the desert [this chapter], is not an "argument for the sake of Heaven," as Korach tried to undermine the entire authority of Judaism. However, when the argument is "for the sake of Heaven" with no personal gain intended, such as the arguments of Hillel and Shammai, who argued in mishnaic times on many points of Jewish law, it is permitted and even encouraged. This type of argument does not undermine peace. In fact, although they disagreed vehemently, the houses of Hillel and Shammai intentionally intermarried to show that they were at peace with each other (Yevamot 14b) (See the chapter "Friendship" for an amplification of this concept). Thus, our goal is the goal mentioned by Zechariah (Zechariah 8:16) that friends should speak in truth to each other, be fair in judgment, and, at the same time, attain peace.