Source: "SACRIFICING THE FEW TO SAVE THE MANY". J. David Bleich, Tradition, Vol. 43, No. 1 (SPRING 2010), pp. 78-86
Finally, from "Preemptive War in Jewish Law" (pp. 3-41), also by Rabbi Bleich:
There are four character types among people. One who says, 'What's mine is mine and what's yours is yours' is of average character, and some say, this is the character of Sodom. [One who says] 'What's mine is yours and what's yours is mine' is unlearned. [One who says] 'What's mine is yours and what's yours is yours' is pious. [One who says] 'What's yours is mine and what's mine is mine' is wicked.'
— Pirkey Avos