“…The families of the sons of Kehos shall camp to the south side of the Mishkan…” – Bamidbar 3:29

מִשְׁפְּחֹת בְּנֵי קְהָת יַחֲנוּ עַל יֶרֶךְ הַמִּשְׁכָּן תֵּימָנָה – במדבר ג, כט

The tribe of Levi camped on all four sides of the Mishkan, and around them the other twelve tribes camped, three tribes on each side. Rashi notes that the tribe of Reuven who camped to the south was particularly affected by the family of Levi’im who camped nearest to them, the family of Kehos—of which the rebellious Korach was a member. In Rashi’s words, “Woe is to the wicked and woe is to his neighbor. This is why Dasan, Aviram, and two hundred and fifty others (of the tribe of Reuven) were smitten with Korach and his band; they were drawn with them into the dispute.”

The Midrash (Tanchuma, Bamidbar 12) makes a similar observation, saying, “‘Woe to the wicked, and woe to his neighbors! … Korach’s neighbor’s in the south were lost along with him in his rebellion.” Notably, unlike Rashi who emphasizes that many Reuvenites joined Korach’s rebellion, the Midrash implies that they were merely punished alongside him. In other words, according to the Midrash, the effects of a wicked neighbor are limited. He does not necessarily cause his innocent neighbor to be evil like him, though he could cause him to be punished along with him or (at most) to be dragged along in his criminal acts.

Concerning a good neighbor, in contrast, even the Midrash agrees that the benefits are more than incidental. For as our Sages taught, “any quality is more powerful when it is used for good than when it is used for evil” (Sotah 11a). Thus, the Midrash observes that, “Moshe, along with Aharon and his sons, encamped in the east, and next to them were Yehudah, Yissachar and Zevulun. On this basis it was said: ‘How fortunate is the righteous, and how fortunate are his neighbors!’ This refers to these three tribes, who were adjacent to Moshe and Aharon, and became great in Torah.” These tribes were impacted by their close proximity to the righteous in a meaningful and life-altering way; in the words of the Midrash, the tribes of Yehudah, Yissachar, and Zevulun themselves “became great in Torah.”

—Likkutei Sichos, vol. 33, pp. 10-15