This commandment is not to be restricted to false testimony given in courts of justice. It prohibits slander, calumny, misrepresentation, at any time, in any circumstances. On the other hand, we shall miss the moral significance of the commandment if we regard it as a prohibition of lying in general. It is a specific kind of falsehood which is forbidden: "false witness against our neighbour."
On what grounds does the commandment fasten on this particular kind of falsehood, instead of condemning falsehood in general? It may be suggested that the bearing of false witness against our neighbour is the most frequent and most injurious kind of falsehood, that the sin of bearing false witness in favour of others is not so common or so mischievous, and that lying to our own advantage is a sin which soon ceases to have any effect.
I. This commandment is a recognition of those tribunals which are necessary to the peace and to the very existence of the State.
II. In this commandment there is a Divine recognition of the importance of the moral judgments which men pronounce on each other: the judgment which individual men form of other men as the result of the testimony to which they have listened, whether it was true or false; the judgments which large classes of men or whole communities form of individuals, and which constitute what we call the opinion of society concerning them.
III. Many ways might be mentioned in which we may avoid bearing false witness against our neighbour. (1) We should try to form a true and just judgment of other people before we say anything against them. (2) We have no right to give our mere inferences from what we know about the conduct and principles of others as though they were facts. (3) We have no right to spread an injurious report merely because somebody brought it to us.
R. W. Dale, The Ten Commandments,p. 218.
References: Exodus 20:16. J. Oswald Dykes, The Law of the Ten Words,p. 171; J. Vaughan, Sermons to Children,4th series, p. 239, S. Leathes, The Foundations of Morality,p. 191; F. D. Maurice, The Commandments,p. 127.