Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

Abimelech then gave him back his wife with a liberal present of cattle and slaves, and gave him leave to dwell wherever he pleased in his land. To Sarah he said, "Behold, I have given a thousand shekele of silver to thy brother; behold, it is to thee a covering of the eyes (i.e., an expiatory gift) with regard to all that are with thee ("because in a mistress the whole family is disgraced," Del.), and with all - so art thou justified." The thousand shekels (about 131) were not a special present made to Sarah, but indicate the value of the present made to Abraham, the amount of which may be estimated by this standard, that at a later date (Exo 21:32) a slave was reckoned at 30 shekels. By the "covering of the eyes" we are not to understand a veil, which Sarah was to procure for 1000 shekels; but it is a figurative expression for an atoning gift, and is to be explained by the analogy of the phrase פּני פ כּפּר "to cover any one's face," so that he may forget a wrong done (cf. Gen 32:21; and Job 9:24, "he covereth the faces of the judges," i.e., he bribes them). ונוכחת can only be the 2 pers. fem. sing. perf. Niphal, although the Dagesh lene is wanting in the ת; for the rules of syntax will hardly allow us to regard this form as a participle, unless we imagine the extremely harsh ellipsis of נוכחת for אתּ נוכחת. The literal meaning is "so thou art judged," i.e., justice has been done thee.