Commentaire sur Le Lévitique 26:37

וכשלו איש באחיו AND THEY SHALL STUMBLE ONE UPON ANOTHER — When they are running in order to escape they will stumble one against the other because they will be in a hurry to run away.

וכשלו איש באחיו, “they will stumble over one another, etc.” According to Sanhedrin 27 the Torah means that they will stumble each over the sins committed by the other, i.e. their reciprocal responsibility which they disregarded became their undoing. This is also what Moses had in mind in Deut. 29,9 when he described each Israelite as “standing upright” at that time, (i.e. not stumbling over his fellow’s sins). The example for this reciprocal responsibility was illustrated most powerfully when because of failure to admonish Achan who had taken money from the loot of Jericho declared sacred for the Temple, this sin became the cause of Israel losing its first campaign after the capture of Jericho. (compare Joshua chapter seven with special emphasis on verse 11) [Contrary to Moses who had asked G’d in connection with Korach why the sin of one man should cause G’d’s anger against a whole nation, in Achan’s case G’d spelled out that it did. Ed.] G’d tells Joshua that “Israel has sinned;” He did not tell him that “an Israelite had sinned.” The whole nation was held responsible for the sin of an individual. An accessory after the fact, i.e. someone who does not admonish the sinner has made himself his partner. Seeing that what Achan had done could not have been concealed completely, there had already been many accessories.
This incident prompted the sages in Shir Hashirim Rabbah 6,16 to comment that the use of the word "nut” in אל גנת האגוז ירדתי, “I went down to the nut-grove” (Song of Songs 6,11), describes that just as it is impossible to pluck one walnut without making the whole tree shake, so it is impossible for an individual to commit a sin without ripples of what he did affecting the entire Jewish people. This is what had bothered Moses in Numbers 16,22: “one man sinned and You are angry at the whole congregation!”

One by the sin of the other. And “As though before a sword” means, just as one stumbles before a sword that pursues after him so he will stumble because of his fellow’s sin (Nachalas Yaakov citing Toras Kohanim). I think the verse is giving a reason for what was said above. Since v. 36 is speaking of “those who survive among you” who are apparently righteous, why then are they punished by “timidity in their hearts,” and that “The sound of a blown leaf will put them to flight and they will flee ... and fall?” Rashi answers, “They will stumble over one another”ùone by the sin of the other, since all Israel is responsible for one another.” Therefore, He will bring these punishments upon them. Gur Aryeh explains that [this interpretation is deduced] because it says, איש באחיו (lit. man against his brother). It should have said “one man against [another] man” or “one man against another,” since it is inappropriate to mention brotherhood in connection with falling [against one another]. But regarding sin it is fitting to write “his brother,” because the reason they will stumble against each other is that all Israel are brothers [i.e., all Israel is responsible for one another].

וכשלו איש באחיו כמפני חרב ורודף אין, “they will stumble upon one another, as if on account of a sword although there is no pursuer;” there is some repetition here.

כמפני חרב AS IT WERE BEFORE THE SWORD — i. e. as though they were fleeing from before murderers. It means that in their heart there will be timidity, and at every moment they will think that somebody is pursuing them. A Midrashic explanation of וכשלו איש באחיו is: one will stumble by reason of the sin of the other (באחיו is taken in the sense of: on account of the other), for all Israelites are held responsible for one another (Sifra, Bechukotai, Chapter 7 5; Sanhedrin 27b).

ולא תהיה לכם תקומה, “you will not have the strength to stand up to your enemies.” This is the fifth curse.