Matthew 5:36-39

36Nor shall you make an oath by your head, for you are not able to make a single hair white or black.

37But let your statement be, ‘Yes, yes’ or ‘No, no’ [a firm yes or no]; anything more than that comes from the evil one.

38“You have heard that it was said, ‘An eye for an eye, and a tooth for a tooth [punishment that fits the offense].’

39But I say to you, do not resist an evil person [who insults you or violates your rights]; but whoever slaps you on the right cheek, turn the other toward him also [simply ignore insignificant insults or trivial losses and do not bother to retaliate—maintain your dignity, your self-respect, your poise].