Musar for Sanhedrin 54:8

And our Sages said, "Everyone for whom it is possible to protest against the sinful things of the people of his household, and he does not protest, is considered guilty of the wrongs of the men of his household. If it is possible for him to protest against the deeds of the people of his city and he does not do so he is held responsible for the wrongs of the people of the city. If it is possible for him to protest against the wrongs of the whole world and he does not do so, then he is considered guilty of the wrongs of all the world" (Shabbath 54b). And it is said, "And they shall stumble one upon another" (Lev. 26:37). And our Rabbis, of blessed memory, explained it as meaning, "Each man for the sin of his brother," which teaches us that all Israel are responsible, one for another (Sanh. 27b).