Pope Pius XI
Quadragesimo Anno §64
Quadragesimo Anno: On Reconstruction of the Social Order
64 First of all, those who declare that a contract of hiring and being hired is unjust of its own nature, and hence a partnership-contract must take its place, are certainly in error and gravely misrepresent Our Predecessor whose Encyclical not only accepts working for wages or salaries but deals at some length with it regulation in accordance with the rules of justice.
Source: Quadragesimo Anno (Vatican.va)