in which he teaches that a person who has no merit of their own has a share in their fellow-person's merit, as they are partners
All Israel have a portion in the World-to-Come. This can be interpreted to mean that since we share the understanding that "All of Israel are responsible for one another", they are to be considered partners in fulfilling the commandments, and in upholding and studying the Torah. And just as partners share benefits, the People of Israel share each other's merit in one another's Torah and good deeds… The Bible does bring evidence: "And your people, all of them are righteous" – and each has her or his own. Should you ever find totally empty people among Israel, they nevertheless "Shall possess the land for all time". "For all time" means that this includes even those who have nothing of their own.