Leviticus 5:1

And if a soul sin
The soul is put for the person, and is particularly mentioned, as Ben Melech says, because possessed of will and desire:

and hear the voice of swearing;
or cursing, or adjuration; not of profane swearing, and taking the name of God in vain, but either of false swearing, or perjury, as when a man hears another swear to a thing which he knows is false; or else of adjuration, either the voice of a magistrate or of a neighbour adjuring another, calling upon him with an oath to bear testimony in such a case; this is what the Jews

and is a witness;
is able to bear witness to the thing he is adjured about:

whether he hath seen or known of it;
what he has seen with his eyes, or knows by any means: of such a case, the Jews observe ^F20, that there may be seeing without knowing, or knowing without seeing, and in either case a man ought to bear witness:

if he do not utter it;
tell the truth, declare what he has seen or known:

then he shall bear his iniquity;
he shall be charged with sin, and be obliged to acknowledge his offence, and bring a trespass offering for it: it is said ^F21, that the witnesses are not guilty of the oath of the testimony, but in these ten cases; if they are required; if the testimony is concerning goods; if the goods are movable; if he that requires binds himself to pay for their testimony only, in case they bear witness; if they refuse after required; if they refuse in the sanhedrim; if the adjuration or oath is made there by the name of God, or his titles; if knowledge of the testimony goes before the oath; if he particularizes his witnesses in the time of the oath, or at the time of the requirement; and if the oath is in a language they understood.

F18 Misn. Sotah, c. 7. 1.
F19 Maimon. & Bartenora in ib. T. Bab. Sotah, fol. 33. 1.
F20 T. Bab. Shebuot, fol. 33. 2. & 34. 1.
F21 Maimon. Hilchot, Shebuot, c. 9. sect. 3.