30 We are offering clerics this total obedience as a model, with full confidence that its force and beauty will lead them to strive for it more ardently. And if there should be someone who dares to cast doubt on the supreme importance of this virtue—as sometimes happens at the present time—let him take to heart these words of Our predecessor of happy memory, Pius XII, which everyone should keep firmly in mind: "The holiness of any life and the effectiveness of any apostolate has constant and faithful obedience to the hierarchy as its solid foundation, basis and support. " (44)
Source: Sacerdotii Nostri Primordia (Vatican.va)