Pope John XXIII
Mater et Magistra §31
Mater et Magistra: On Christianity and Social Progress
31 As for the wage system, while rejecting the view that it is unjust of its very nature, he condemned the inhuman and unjust way in which is it so often implemented, and specified the terms and conditions to be observed if justice and equity are not to be violated.
Source: Mater et Magistra (Vatican.va)