Genesis 20:16

And to Sarah he said, Behold, I have given a thousand sileen of silver to thy brother; behold, they are to thee a veil of the eyes, inasmuch as thou wast hidden from thine husband one night, and I would have seen thee: for were I to give all that I have it would not suffice (or be proportionate). And the words were debated. And Abraham knew that Abimelek had not come near Sarah his wife.

BEHOLD, I HAVE GIVEN THY BROTHER A THOUSAND PIECES OF SILVER. The sheep, the cattle and the servants which he gave him were worth a thousand pieces of silver. He thus said to Sarah: “Behold, I have given much money to your brother. Now the money will serve you as a cause for the covering of the eyes of all those who look at your beauty, closing their eyes, and those of their leaders, the seers,. to prevent them looking at you and at all that belongs to you, even your manservants and maidservants. Thus your being taken forcibly to my house was for your benefit as they will fear you and cover their eyes to avoid looking at you, saying: ‘The king had to redeem himself for having stretched forth his hand to the prophet’s wife.’”
The verse thus tells that Abimelech mollified Abraham with money, and Sarah with words, so that he should not be punished on account of either of them. The verse states in conclusion, venochachath, as Sarah did not accept his apology, for with all this, she yet continued arguing with him, saying that she would not forgive him. The verse thus speaks in her praise. Abraham, however, was appeased, and he prayed for the king. The word venochachath is similar in usage to these verses: And with Israel ‘yithvakach’ (He has an argument); But my ways ‘ochiach’ (will I argue) before Him; There the upright ‘nochach’ (might reason) with Him., 23:7.
It is possible that the expression, a thousand pieces of silver to thy brother, means thousands of pieces of silver, much wealth, according to the bounty of the king. Similarly, The smallest shall become a thousand, [means that the smallest will become] a great people. Similarly: Restore, I pray you, to them even this day, their fields, their vineyards, their oliveyards, and their houses, also the hundred pieces of silver, and the corn, the wine, and oil, that ye exact of them — [here too the hundred pieces of silver refer to] many hundreds, a great deal of money.

ולשרה אמר, words of appeasement and consolation, explaining to her that when he had first taken her he had not employed forceful means but had treated her as if she had been a willing bride, giving her a dowry as was customary in those days for the groom to do. He had given 1000 pieces of silver to her brother, seeing that he had assumed that Avraham was no more than her brother to her as he had been led to believe. She herself had said so. This is not to be confused with the livestock which Avimelech gave Avraham at the conclusion of this story, the gifts mentioned in verse 14. The 1000 pieces of silver he had given before Sarah was taken to his palace. Even Pharaoh who had been punished more severely had made generous gifts not only to Avraham but even Lot had been enriched. (12,15). All this had been before any marriage ceremony. Avimelech clearly had been at least as generous.

נתתי אלף כסף, the distant past tense, i.e. “I had given it “ at the very beginning. The same sequence occurred when Pharaoh abducted Sarah, and the same procedure was offered by Shechem and Chamor in Genesis 34,12 as part of the offer to marry Dinah. Also, in Genesis 24,53 we find Eliezer making such generous gifts prior to obtaining Lavan’s consent for Rivkah to marry Yitzchok.

הנה הוא לך כסות עינים לכל אשר אתך ואת כל, the thousand pieces of silver I had given to your brother represent a great honour for you, and they will serve as proof for one and all that you have not been disgraced in any way. Nobody will ever be able to claim that you have been treated as helpless, as a woman who had no honour to lose.

כסות עינים, they will not be able to look at you as someone who had been discredited. We find the word כסה used in a similar sense in Exodus 10,5 וכסה את עין הארץ, “it (the locust) will cover the visible part of the earth, i.e. the earth will not be “naked,” “exposed.” A similar sequence appears in this sense in Ezekiel 28,17 לראוה בך, “so that they may gaze upon,” (not turn away in shame and disgust). The expression also occurs in a similar sense in Micah 7,10 עיני תראינה בה, “my eyes shall behold her.”

ונוכחת, you will be able to hold your head high in view of the fact that you have been treated with so much honour and respect. Avimelech said all this in honour of Sarah and not as a rebuke to her.

הנה נתתי אלף כסף לאחיך, as dowry, as was the custom for any groom marrying the daughter or sister of a man.

הנה לך כסות עינים, clothing consisting of a variety of colours which women used to wear as a mark of distinction. The dowry he gave her brother was intended to show that he did not consider her a whore but someone reputable, and that he did not mean her to be his concubine but his regular wife. Also, he meant that he would not have let Sarah go so easily except for Divine intervention which forced him to let her go.

לכל אשר אתך, before the eyes of everybody, so that they know in your household that everything is above board.

ואת כל ונוכחת, and you will be perceived exonerated in every respect even in the eyes of those who would have felt tempted to interpret what happened to you in a negative light, reflecting discredit upon you.

ולשרה אמר הנה נתתי אלף כסף, in addition to the livestock, men and women servants he had given Avraham, mentioned in verse 14. The purpose of the cash was to enable her to buy herself elegant clothing.

וכל אשר אתך, all your entourage should also have been outfitted with elegant clothing. Anyone belonging to your household was meant to look their best thanks to this money I gave to your brother.

לאחיך, to the person you had described to me as “your brother.”

כסות עינים, something appealing to your eyes and all those who look at you. Your brother was supposed to use this money to buy such garments for you. What are meant are specifically coloured garments, as the word עינים frequently describes gay colours. Compare the Torah’s description of the appearance of the manna in Numbers 11,7 as ועינו כעין הבדולח, “and its colour like the colour of crystal.” Or, Ezekiel 1,16 כעין תרשיש, “as the colour of beryl.” It is possible that the embroidering on the garment consisted of a variety of colours.

ואת כל ונוכחת, the Torah tells its readers that after all that Sarah had experienced at the hands of Pharaoh and Avimelech, she never again described Avraham as her brother instead of as her husband. If the word ונוכחת were to be understood as part of what Avimelech had said to Sarah, the letter ת at the end of this word would have required to have a dot, dagesh in it, whereas it is spelled “weak,” i.e. without such a dagesh, to indicate that it is in a third person feminine mode and not part of direct speech, second person feminine. (compare a similar construction in Isaiah 23,15)

הנה נתתי אלף כסף לאחיך, “here I have given one thousand silver pieces to your brother;” The root אלף has different meanings in different contexts. For instance, in Job 33,33, ואאלפך חכמה, it means: “I will teach you wisdom.” It also appears as an expression for excessive desire, as in Genesis 31,30: כי נכסוף נכספת, where Lot acknowledges Yaakov’s great “longing to return to his father’s home after so many years of absence.” In our verse the correct interpretation is that Avimelech having given this amount of silver to Sarah’s brother Avraham who had told him that he was her brother, means that it should teach her a lesson to really love him. An alternate interpretation is that it is used as an expression for craving after material wealth as in Deuteronomy 7,13: שגר אלפיך, “the exceptional increase in your flocks and sheep, the example quoted by Rashi who says that it is a metaphor for riches, something nearly everyone is craving for. הנה לך כסות עינים, “here it shall serve you as a cover for the eyes;” Avimelech refers to the word אחיך, saying that Sarah had described her husband as her brother out of a sense of chastity. Had she referred to him as “my husband,” anyone hearing her say this would immediately have understood it as “my sexual partner.” She was too chaste to refer to anyone other than to her husband in such terms.

ואת כל ונוכחת, “and you will be found justified before all and sundry.” Avimelech warns her that not everyone understands such lofty moral standards; therefore they would have taken you at your word, not knowing that they were a metaphor. In future, therefore, she is not to mislead people by describing her husband as her brother. The only people who do not misunderstand your reference to your ”brother”, are the ones that are part of your household. Beware not to be the source of being so misunderstood.