Nicene and Post-Nicene Fathers, Vol. III:
Moral Treatises of St. Augustin: Section 17

17. Only by this, which I have briefly set down, the reader ought to be set on his guard against those, who, in this that is written, “but such shall have tribulation of the flesh but I spare you,” falsely charge marriage, as indirectly condemned by this sentence; as though he were unwilling to utter the condemnation itself, when he saith, “But I spare you;” so that, forsooth, when he spares them, he spared not his own soul, as saying falsely, “And, if thou shalt have taken a wife, thou hast not sinned; and if a virgin shall have been married, she sinneth not.” And this, whoso believe or would have believed concerning holy Scripture, they, as it were prepare for themselves a way for liberty of lying, or for defense of their own perverse opinion, in whatever case they hold other sentiments than what sound doctrine demands. For if there shall be alleged any plain statement from the divine books, whereby to refute their errors, this they have at hand as a shield, whereby defending themselves as it were against the truth, they lay themselves bare to be wounded by the devil: to say that the author of the book did not speak the truth in this instance, at one time in order to spare the weak, at another in order to alarm despisers: just as a case shall come to hand, wherein to defend their own perverse opinion: and thus, whilst they had rather defend than amend their own opinions, they essay to break the authority of holy Scripture, whereby alone all proud and hard necks are broken.