Musar zu Jeschijahu 21:5

And now we will explain the matter of the punishment of those that separate from the ways of the community, and that he is included in the punishments of the groups that we mentioned above: When the heads of the people and the holy communities gather to serve God, may He be blessed, and make agreements to place commandments upon themselves - they are surely sanctifying God, may He be magnified and sanctified, as it is stated (Deuteronomy 33:5), “Then He became King in Jeshurun, when the heads of the people assembled, the tribes of Israel together.” And it is [also] stated (Psalms 47:10), “The great of the peoples are gathered together, the people of Abraham’s God; for the shields of the earth belong to God; He is greatly exalted.” Israel is called, “peoples,” because they are twelve tribes, like the matter that is stated (Deuteronomy 33:19), “They invite the peoples to the mountain.” But they are one people to serve God; therefore is it stated, “the people of Abraham’s God.” And the kings and the officers are called, “shields,” from the usage (Isaiah 21:5), “grease the shields.” The explanation of [Psalms 47:10] is, the great of the peoples gathered together to serve God, may He be exalted, because their kings and their officers are for God - as they are His servants and His faithful, like the matter that is stated (Psalms 89:19), “Truly our shield is of the Lord, our King, of the Holy One of Israel.” “He is greatly exalted,” since the Holy One, blessed be He, is exalted and glorified in His world in their gathering together and in their service. And the man that separates from the ways of the community is like an opponent of the agreement about the service of God; and like one who exits from the aggregate that is sanctifying God. So he shows himself to not want to be in their council, nor be written in their writings. Behold he is [thus] among those that profane the service and is included in the groups that we mentioned - that are scorning the word of God, and do not have a share in the world to come. And secondly, they dissuade the heart of the weak-minded by their separating from the ways of the community, and so are among those that cause the many to sin.