I. That this commandment was intended, as some suppose, to forbid the infliction of capital punishment, is inconceivable. The Mosaic law itself inflicted death for murder, Sabbath-breaking, and the selling of a Jew into slavery. The root of the commandment lies in the greatness of human nature; man is invested with a supernatural and Divine glory; to maintain the greatness of man it may be sometimes necessary that the murderer, who in his malice forgets the mystery and wonderfulness of his intended victim, should be put to death.
II. Does the commandment absolutely forbid war between nations? Certainly not. The nation to which it was given had a strict military organisation, organised by the very authority from which the commandment came. Moses himself prayed to God that the hosts of Israel might be victorious over their enemies. Wars of ambition, wars of revenge these are crimes. But the moral sense of the purest and noblest of mankind has sanctioned and honoured the courage and heroism which repel by force of arms an assault on a nation's integrity, and the great principle which underlies this commandment sanctions and honours them too.
R. W. Dale, The Ten Commandments,p. 146.
References: Exodus 20:13. J. Oswald Dykes, The Law of the Ten Words,p. 123; S. Leathes, The Foundations of Morality,p. 154; F. D. Maurice, The Commandments,p. 87. Exodus 20:13-16. Parker, The City Temple,vol. i., p. 320, also The Contemporary Pulpit,vol. iii., p. 122: Preacher's Monthly,vol. ii., p. 215.