Pope Paul VI
Sacerdotalis Caelibatus §9
Sacerdotalis Caelibatus: On the Celibacy of the Priest
9 Then there are those who are convinced that a married priesthood would remove the occasions for infidelity, waywardness and distressing defections which hurt and sadden the whole Church. These also maintain that a married priesthood would enable Christ's ministers to witness more fully to Christian living by including the witness of married life, from which they are excluded by their state of life.
Source: Sacerdotalis Caelibatus (Vatican.va)