Adam Clarke's Bible Commentary Verse 7. He said, She is my sister] It is very strange that in the same place, and in similar circumstances, Isaac should have denied his wife, precisely as his father had done before him! It is natural to ask, Did Abraham never mention this circumstance to his son? Probably be did not, as he was justly ashamed of his weakness on the occasion-the only blot in his character; the son, therefore, not being forewarned, was not armed against the temptation. It may not be well in general for parents to tell their children of their former failings or vices, as this might lessen their authority or respect, and the children might make a bad use of it in extenuation of their own sins. But there are certain cases, which, from the nature of their circumstances, may often occur, where a candid acknowledgment, with suitable advice, may prevent those children from repeating the evil; but this should be done with great delicacy and caution, lest even the advice itself should serve as an incentive to the evil. I had not known lust, says St. Paul, if the law had not said, Thou shalt not covet.
Isaac could not say of Rebekah, as Abraham had done of Sarah, She is my sister; in the case of Abraham this was literally true; it was not so in the case of Isaac, for Rebekah was only his cousin. Besides, though relatives, in the Jewish forms of speaking, are often called brothers and sisters, and the thing may be perfectly proper when this use of the terms is generally known and allowed, yet nothing of this kind can be pleaded here in behalf of Isaac; for he intended that the Gerarites should understand him in the proper sense of the term, and consequently have no suspicion that she was his wife. We have already seen that the proper definition of a lie is any word spoken with the intention to deceive. See Genesis xx. 12.
Matthew Henry Commentary
Verses 6-11 - There is nothing in Isaac's denial of his wife to be imitated, nor eve excused. The temptation of Isaac is the same as that which overcame his father, and that in two instances. This rendered his conduct the greater sin. The falls of those who are gone before us are so man rocks on which others have split; and the recording of them is lik placing buoys to save future mariners. This Abimelech was not the sam that lived in Abraham's days, but both acted rightly. The sins of professors shame them before those that are not themselves religious.
Original Hebrew וישׁאלו7592 אנשׁי376 המקום4725 לאשׁתו802 ויאמר559 אחתי269 הוא1931 כי3588 ירא3372 לאמר559 אשׁתי802 פן6435 יהרגני2026 אנשׁי376 המקום4725 על5921 רבקה7259 כי3588 טובת2896 מראה4758 הוא׃1931
