Therefore in his writings, as writing allows of greater circumspection, the Apostle is found to have used an oath in several places, that none might suppose that there is any direct sin in swearing what is true; but only that our weak hearts are better preserved from perjury by abstaining from all swearing whatever.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: cont. Faust., xix, 23