… is from page 185 of F.A. Hayek’s April 1938 Contemporary Review essay, “Freedom and the Economic System,” as this essay is reprinted as chapter eight of the 1997 collection, edited by Bruce Caldwell, Socialism and War (footnote deleted):
The decision on the relative importance of conflicting aims is necessarily a decision about the relative merits of different groups and individuals. [Economic] Planning [by government] becomes necessarily a planning in favour of some and against others.