… is from page 256 of Milton Friedman’s 1958 essay “Capitalism and Freedom,” which is Chapter 8 in Essays on Individuality , Felix Morley, ed. (Indianapolis: Liberty Press, 1977 ; link added):
[T]he groups in our society that have the most at stake in the preservation and the strengthening of competitive capitalism are those minority groups which can most easily become the object of distrust and enmity of the majority – the Negroes, the Jews, the foreign born, to mention only the most obvious. Yet, paradoxically enough, the enemies of the free market – the socialists and Communists – have been recruited in disproportionate measure from these groups. Instead of recognizing that the existence of the market has protected them from the attitudes of their fellow countrymen , they mistakenly attribute the residual discrimination to the market.
Were he still alive, Milton Friedman  would today celebrate his 101st birthday.