Deuteronomy 21:1

If one be found slain,.... After public war with an enemy, Moses proceeds to speak of a private quarrel and fight of one man with another, in which one is slain, as Aben Ezra observes:

in the land which the Lord thy God giveth thee to possess it; where murders might be committed more secretly, and remain undiscovered, when they came to live in separate cities, towns, and villages, with fields adjacent to them, than now encamped together:

lying in the field; where the quarrel begun, and where the fight was fought: or, however, where the murderer met with his enemy, and slew him, and left him; it being common for duels to be fought, and murders committed in a field; the first murder in the world was committed in such a place, Genesis 4:8. The Targum of Jonathan is,

"not hidden under an heap, not hanging on a tree, nor swimming on the face of the waters;''

which same things are observed in the Misnah i, and gathered from some words in the text:

in the land, and so not under a heap;

lying, and so not hanging;

in the field, and so not swimming on the water:

and it be not known who hath slain him; the parties being alone, and no witnesses of the fact, at least that appear; for, if it was known, the heifer was not beheaded, later mentioned k; and one witness in this case was sufficient, and even one that was not otherwise admitted.

i Sotah, c. 9. sect. 2. k Maimon. Hilchot Rotzeach, c. 9. sect. 11, 12.