Rashi on TanakhDeuteronomy 21

Your elders shall go out. The most distinguished of your elders. This refers to the supreme Sanhedrin.

And measure. From the spot where the corpse is lying.

In the direction of the cities around the corpse. In every direction, in order to determine which is closest.

To a stony valley. Hard, which cannot be cultivated.

They shall decapitate. By severing the nape with an axe. The Holy One, may He be blessed, said, ‘Let a yearling calf, which never bore fruit, come and be decapitated in a place which cannot bear fruit, as atonement for the murder of the one who was not permitted to bear fruit.

Our hands have not spilled. Is it possible to imagine that the elders of the court committed murder? Rather, ‘We did not observe him and dismiss him without food and escort.’ The kohanim then say:

Forgive your people Yisroel: The blood shall thus be atoned for in their behalf. Scripture informs them that once they have fulfilled this, the sin will be absolved.

Still, you must eradicate. This teaches that if the murderer is apprehended after the decapitation of the heifer, he must be executed. This is righteous in the eyes of God.

If you should go to war. Optional warfare is Scripture’s subject; for, with regard to the war for Eretz Yisroel, it would be inappropriate to say, “and you capture prisoner from them,” since it has already said, “Do not allow a soul to remain alive.”

And you capture prisoners from them. This includes the Canaanites among them, although they are members of the seven nations.

A wife. Even someone’s wife.

You may take her as your wife. The Torah speaks only in deference to the wicked inclination, for if the Holy One, blessed is He, would not permit her, he would live with her illicitly. However, if he does marry her, he will ultimately hate her, as it is further said, “If a man has, etc.” And, ultimately, he will father, from her, a wayward, rebellious son. This is why these chapters adjoin one another.

And allow her nails to grow. She must allow them to grow so that she becomes ugly.

She must discard her prisoner’s garb. As they are attractive, since the young Gentile women beautify themselves during warfare, to invite promiscuous behaviour with them.

And she will remain in your home. In the home he makes use of. He enters and stumbles over her, leaves and stumbles over her, notices her weeping and disgrace, so that she becomes repulsive to him.

And weep for her father. Why to such an extent? So that the Israelite daughter may be joyous, while this one is melancholy; the Israelite daughter may beautify herself, while this one becomes ugly.

But it shall come to pass, that if you do not desire her. Scripture informs you that you will ultimately hate her.

You may not exploit her. You may not utilize her. In the Persian language, servitude and utilization is verbalized as imra’ah. From the commentary of R’ Moshe Hadarshan I have learned this.

Doublefold. Equivalent to two brothers.

Of all that he possesses. From here [we derive] that the firstborn does not inherit doublefold of receivables due after the father’s death, as he does of property in his possession.

Wayward. Who strays from the path.

And rebellious. Who rebels against his father’s instructions. The word means the same as “rebels.”

Though they chasten him. They warn him before three [magistrates] and have him flogged. The wayward, rebellious son is not liable unless he steals and consumes a tartamor of meat, and drinks half a log of wine, as it is said, “gluttonous and drunken,” and it is said, ”Do not be among the wine guzzlers, among those who gluttonously consume meat for themselves.” The wayward, rebellious son is executed in consideration of his ignoble end. The Torah penetrates to the logical conclusion of his thought — ultimately, he will squander his father’s fortune, attempt to apply himself to his studies and fail, station himself near an intersection and plunder his fellow creatures; the Torah declares: Let him die in innocence rather than die laden with guilt.

Let all Yisroel hear and be fearful. From here [we derive] that there must be a proclamation at the courthouse: ‘So-and-so was stoned for having been a wayward, rebellious son’!

If a man is guilty of a capital offense. The proximity of the chapters teaches that if his mother and father take pity on him, he will ultimately develop into a degenerate, commit transgressions, and be sentenced to death by the courts.

You shall hang him from a tree. The Rabbis remark that all those who are stoned are also hung, for it is said, “for a hanging corpse is an affront to God,” and someone who curses God is stoned.

For a hanging corpse is an affront to God. It is an affront to the king, for man is fashioned in His image, and the Israelites are His children. This is compared to twin brothers who were identical to each other. One became king, and one was apprehended as a thief and hanged. Everyone who saw him exclaimed, ‘The king has been hanged!’ [The king issued a command, and he was brought down.] קְלָלָה throughout Scripture connotes slighting and insult, as in, “He insulted me explicitly.”