Having forbidden swearing, He instructs us how we ought to speak, “Let your speech be yea, yea; nay, nay.” That is, to affirm any thing it is sufficient to say, ‘It is so;’ to deny, to say, ‘It is not so.’
Or, “yea, yea; nay, nay,” are therefore twice repeated, that what you affirm with the mouth you should prove in deed, and what you deny in word, you should not establish by your conduct.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).