Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Deu 21:1-9) The expiation of uncertain murder.
(Deu 21:10-14) Respecting a captive taken to wife.
(Deu 21:15-17) The first-born not to be disinherited for private affection.
(Deu 21:18-21) A stubborn son to be stoned.
(Deu 21:22, Deu 21:23) Malefactors not to be left hanging all night.
If a murderer could not be found out, great solemnity is provided for putting away the guilt from the land, as an expression of dread and detesting of that sin. The providence of God has often wonderfully brought to light these hidden works of darkness, and the sin of the guilty has often strangely found them out. The dread of murder should be deeply impressed upon every heart, and all should join in detecting and punishing those who are guilty. The elders were to profess that they had not been any way aiding or abetting the sin. The priests were to pray to God for the country and nation, that God would be merciful. We must empty that measure by our prayers, which others are filling by their sins. All would be taught by this solemnity, to use the utmost care and diligence to prevent, discover, and punish murder. We may all learn from hence to take heed of partaking in other men's sins. And we have fellowship with the unfruitful works of darkness, if we do not reprove them.
By this law a soldier was allowed to marry his captive, if he pleased. This might take place upon some occasions; but the law does not show any approval of it. It also intimates how binding the laws of justice and honour are in marriage; which is a sacred engagement.
This law restrains men from disinheriting their eldest sons without just cause. The principle in this case as to children, is still binding to parents; they must give children their right without partiality.
Observe how the criminal is here described. He is a stubborn and rebellious son. No child was to fare the worse for weakness of capacity, slowness, or dulness, but for wilfulness and obstinacy. Nothing draws men into all manner of wickedness, and hardens them in it more certainly and fatally, than drunkenness. When men take to drinking, they forget the law of honouring parents. His own father and mother must complain of him to the elders of the city. Children who forget their duty, must thank themselves, and not blame their parents, if they are regarded with less and less affection. He must be publicly stoned to death by the men of his city. Disobedience to a parent's authority must be very evil, when such a punishment was ordered; nor is it less provoking to God now, though it escapes punishment in this world. But when young people early become slaves to sensual appetites, the heart soon grows hard, and the conscience callous; and we can expect nothing but rebellion and destruction.
By the law of Moses, the touch of a dead body was defiling, therefore dead bodies must not be left hanging, as that would defile the land. There is one reason here which has reference to Christ; "He that is hanged is accursed of God;" that is, it is the highest degree of disgrace and reproach. Those who see a man thus hanging between heaven and earth, will conclude him abandoned of both, and unworthy of either. Moses, by the Spirit, uses this phrase of being accursed of God, when he means no more than being treated most disgracefully, that it might afterward be applied to the death of Christ, and might show that in it he underwent the curse of the law for us; which proves his love, and encourages to faith in him.