פירוש על ויקרא 5:1

‎‏‎ קול האלה ‎ה‎ושמע‎ [AND IF A SOUL SIN] AND HEAR THE VOICE OF AN OATH in a matter to which he was witness, i. e. that he (the person interested in the evidence) called upon him (the witness) by an oath that if he knows any evidence favourable to him he should testify for him before the court (cf. Sifra); if he does not tell it, he bears his iniquity.

AND HE IS A WITNESS, WHETHER HE HATH SEEN OR KNOWN³³²The section here discusses the offering of higher or lower value (see above, Note 15), the verse before us stating that this offering is required in the case of a false oath concerning testimony. Thus, if the person interested in the evidence called upon him by an oath, adjuring him that if he knows any evidence favorable to him he should testify before the court, and he swore that he knows of no testimony concerning him, when in fact he does know, in such a case, if he swore either unintentionally or wilfully, he must offer what is called an offering of higher or lower value. See “The Commandments,” Vol. I, pp. 82-83. In the following verse another transgression for which this offering is required is mentioned. — Ramban now proceeds to explain the sense of the triple expression, and he is a witness, or knows, or saw. These are not three separate matters, for it is impossible that one be a witness without seeing and knowing. Rather, Scripture is stating that if one hear the voice of adjuration that a party to a law-suit adjures him, concerning a matter in which he is a witness either by seeing or knowing of it, if he does not tell it he has committed an iniquity. Now the witness is not obligated to bring this offering unless he knows such a testimony that the party in suit who adjured him [to give witness] would have legally won his case because of it [and the witness nonetheless withheld his evidence]. It is for this reason that our Rabbis³³³Shebuoth 33b. interpreted [on the basis of the verse before us] that there is testimony which is valid by seeing without knowing, and [testimony which is valid] by knowing without seeing. How so? [Reuben says to Shimon:] “I have delivered to thee a maneh³³⁴A Hebrew unit of weight and value, equal to the sixtieth part of a talent. [as a loan] in the presence of such-and-such persons,” and [Shimon] claims “this never happened,³³⁵And Shimon claims: “Let such and such persons come and testify that they saw you [Reuben] delivering me the money, and I will pay you” (Rashi, ibid.). let the witnesses [you claim to have], come and testify.” This is a case of seeing without knowing [since although they saw Reuben handing the money to Shimon, they do not know the nature of this delivery, whether it was as a loan, or repayment of a loan that Shimon had originally made to him].³³⁶But since Shimon denied that this transaction had ever taken place, and says that if Reuben can produce the witnesses he claims he has to testify that they saw Reuben delivering him money, he will pay Reuben — then the witnesses’ testimony that they saw Reuben giving Shimon money is sufficiently valid to obligate Shimon to pay Reuben, although they did not know the nature of that transaction. If therefore they withhold their testimony, they are liable to bring the offering dealt with here. [If Reuben says to Shimon:] “You have admitted to owing me a maneh,³³⁴A Hebrew unit of weight and value, equal to the sixtieth part of a talent. in the presence of such-and-such persons,” [and Shimon replies]: “let them come and testify,” this is a case of knowing without seeing [and even though they did not see, they must testify what they know, and hence are liable if they withhold their evidence].
But in line with the plain meaning of Scripture, we need not [explain] the “seeing” here [to mean seeing] without knowing. Rather, the sense of the verse is as follows: whether he hath seen, meaning that he saw the loan or the sale completely [i.e., with knowledge], or known, i.e., that he heard [the defendants to the suit] admitting that transaction in the presence of witnesses, but he did not see it.
Now He does not state here: “and it is hidden from him,” [as He does in the following verse], because in this case [where the witness swears that he knows of no testimony for the party that adjures him to come and testify before the court], he is obligated to bring the offering [mentioned here in these verses] whether he swore [entirely] wilfully, or was in error on the oath whilst wilfully denying his knowledge of evidence. If, however, at the time of giving the oath he had forgotten the testimony, there is no guilt upon him.

כי תחטא, if one sins, etc. Why did the Torah have to introduce this paragraph with the words ונפש כי תחטא ושמעה?, It would have sufficed to write ונפש כי תשמע. Perhaps the reason is that the person who is the subject of this paragraph is one who had previously denied knowing of testimony which could result in an accused's exoneration. When he does so a second time, he proves that he had already incriminated himself previously. The Torah alludes to this state of affairs by writing נפש כי תחטא, someone who has already sinned, etc. The fact that the potential witness had lied already previously is accounted as a sin. All of this is confirmed by the letter ו the beginning of the word ונפש, at the start of this paragraph.