Humani Generis Redemptionem §13

¹³ The same severity is to be shown towards those who fail to preach properly because they have neglected the acquisition of whatever is necessary for performing this function becomingly. What these conditions are We may learn from the example of him whom the Church has called "the Preacher of truth," the Apostle St. Paul. Would that by God's mercy We might have many more preachers like him!