I’m really on a roll now! From Augustine’s Teaching Christianity, Book IV:
But anyone who says that people do not need to be given rules about what or how they should teach, if the Holy Spirit is making them teachers, can also say that we do not need to pray either, because the Lord said, ‘Your Father knows what you need before you ask it of him (Mt 6:8);’ or that the apostle Paul should not have instructed Timothy and Titus on how they were to instruct others – three letters of the Apostle, by the way, which anyone charged with the role of teacher in the Church ought always to have before his eyes.”
Teaching Christianity, Tr. Edmund Hill (Hyde Park, NY: New City Press), 219 [emphasis mine].