Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
The elders represented the citizens at large, the judges the magistracy: priests Deu 21:5 from the nearest priestly town, were likewise to be at hand. Thus, all classes would be represented at the purging away of that blood-guiltiness which until removed attached to the whole community.
The requirements as regards place and victim are symbolic. The heifer represented the murderer, so far at least as to die in his stead, since he himself could not be found. As hearing his guilt the heifer must therefore be one which was of full growth and strength, and had not yet been ceremonially profaned by human use. The Christian commentators find here a type of Christ and of His sacrifice for man: but the heifer was not strictly a sacrifice or sin-offering. The transaction was rather figurative, and was so ordered as to impress the lesson of Gen 9:5.
Eared - i. e., plowed; compare Gen 45:6 note and references. The word is derived from the Latin, and is in frequent use by English writers of the fifteenth and two following centuries.
Strike off the heifer's neck - Rather, "break its neck" (compare Exo 13:13). The mode of killing the victim distinguishes this lustration from the sin-offering, in which there would be of course shedding and sprinkling of the blood.
The regulations which now follow in the rest of this and throughout the next chapter bring out the sanctity of various personal rights and relations fundamental to human life and society.
Deu 21:10-14. The war supposed here is one against the neighboring nations after Israel had utterly destroyed the Canaanites (compare Deu 7:3), and taken possession of their land.
The shaving the head (a customary sign of purification, Lev 14:8; Num 8:7), and the putting away "the garment of her captivity," were designed to signify the translation of the woman from the state of a pagan and a slave to that of a wife among the covenant-people. Consistency required that she should "pare" (dress, compare Sa2 19:24), not "suffer to grow," her nails; and thus, so far as possible, lay aside everything belonging to her condition as an alien.
Bewail her father and her mother a full month - This is prescribed from motives of humanity, that the woman might have time and leisure to detach her affections from their natural ties, and prepare her mind for new ones.
Thou shalt not make merchandise of her - Rather, thou shalt not constrain her: literally "treat her with constraint," or "treat her as a slave."
Moses did not originate the rights of primogeniture (compare Gen 25:31), but recognized them, since he found them pre-existing in the general social system of the East. Paternal authority could set aside these rights on just grounds Gen 27:33, but it is forbidden here to do so from mere partiality.
The formal accusation of parents against a child was to be received without inquiry, as being its own proof. Thus the just authority of the parents is recognized and effectually upheld (compare Exo 20:12; Exo 21:15, Exo 21:17; Lev 20:9); but the extreme and irresponsible power of life and death, conceded by the law of Rome and other pagan nations, is withheld from the Israelite father. In this, as in the last law, provision is made against the abuses of a necessary authority.
There were four methods of execution in use among the ancient Jews; stoning (Exo 17:4; Deu 13:10, etc.), burning Lev 20:14; Lev 21:9, the sword Exo 32:27, and strangulation. The latter, though not named in Scripture, is regarded by the rabbis as the most common, and the proper one to be adopted when no other is expressly enjoined by the Law. Suspension, whether from cross, stake, or gallows, was not used as a mode of taking life, but was sometimes added after death as an enhancement of punishment. Pharaoh's chief baker Gen 40:19 was hanged after being put to death by the sword; and similarly Joshua appears Jos 10:26 to have dealt with the five kings who made war against Gibeon. Compare also Num 25:4.
He that is hanged is accursed of God - i. e. "Bury him that is hanged out of the way before evening: his hanging body defiles the land; for God's curse rests on it." The curse of God is probably regarded as lying on the malefactor because, from the fact of his being hanged, be must have been guilty of a especially atrocious breach of God's covenant. Such an offender could not remain on the face of the earth without defiling it (compare Lev 18:25, Lev 18:28; Num 35:34). Therefore after the penalty of his crime had been inflicted, and he had hung for a time as a public example, the holy land was to be at once and entirely delivered from his presence. See Gal 3:13 for Paul's quotation of this text and his application of it.