John Calvin on Matthew 5:37

37. But your speech shall be, Yes, yes; No, no Christ now prescribes, in the second place, a remedy; which is, that men act towards each other sincerely and honestly: for then simplicity of speech will have quite as much weight as an oath has among those who are not sincere. Now, this is certainly the best way of correcting faults, to point out the sources from which they spring. Whence comes the great propensity to swearing, but from the great falsehood, the numerous impositions, the unsteady and light conduct, so that hardly any thing is believed? “D’ou vient une si grande legerete en sermens, sinon qu'entre tout de mensonges, tromperies, inconstance et babil, on ne sait qui croire, ni a qui se fier?” — “Whence comes so great a lightness about oaths, but that among so many lies and impositions, and so much unsteadiness and trifling, one does not know whom to believe or whom to trust?” Fairness and honesty in our words are, therefore, demanded by Christ, that there may be no longer any occasion for an oath.

“Yes, yes; No, no.” This repetition means, that we ought to abide by our words, so that all may be convinced of our honesty. Now, as this is the true and lawful method of proceeding, when men have nothing on their tongue but what is in their heart, Christ declares, that what is beyond these comes from evil I do not approve of the exposition of these words which some have given, that the criminality of swearing ought to be charged on the man who does not give credit to what another says. Christ teaches us, in my opinion, that it originates in the wickedness of men, that they are compelled to swear: for, if honesty prevailed among men, if they were not inconsistent and hypocritical, they would maintain that simplicity which nature dictates. And yet it does not follow, that it is unlawful to swear, when necessity demands it: for many things are proper in themselves, though they have had a wicked origin.

MATTHEW 5:38-41; LUKE 6:29-30

Matthew 5:38-41

Luke 6:29-30

38. You have heard that it was said, An eye for an eye, and a tooth for a tooth. 39. But I say to you, Do not resist evil: but whoever, shall inflict a blow on thy right cheek, turn to him the other also: 40. And to him who wishes to enter into a law-suit with thee, and to take away thy coat, allow him thy cloak also: 41. And whoever shall constrain thee to one mile, go with him two.

29. To him who striketh thee on one cheek offer also the other, and from him who taketh away thy cloak, do not forbid thy coat also. 30. And to every one that asketh from thee give; and from him who takes what are thine, do not ask them again.