Genesis 20:13

At every place. This was not the first occasion on which Abraham had passed Sarah off as his sister. It would almost seem to have been his usual practice, but that heretofore Egypt had been the only place where the ruse caused trouble. Years of success in employing the same deception, since that bitter experience with Pharaoh, had made Abraham forgetful of its lesson of strict rectitude (see Eccl. 8:11). Perhaps the comparative ease with God had rescued him from serious difficulty also tended to make him less cautious.

The secluded life of women, typical in the East, made it relatively easy for Abraham to follow the practice he did. Spending much of their time in the tents, beyond the gaze of curious eyes, few men ever even so much as saw them (see Gen. 18:9). Abimelech’s contact with her must have been accidental, possibly at an unguarded moment when she was away from home, such as drawing water at a public well (see ch. 34:1-4). However that may be, the time for the birth of the promised seed was rapidly approaching (see ch. 21:1), and Satan took advantage of Abraham’s weakness to thwart the divine plan (see on Gen. 12:12-20; cf. Rev. 12:1-4).