Genesis 20:2-3

"And Abraham said of Sarah his wife, She is my sister: and Abimelech sent, and took Sarah. But God came to Abimelech in a dream of the night, and said to him, Behold, thou art but a dead man, because of the woman thou hast taken; for she is a man's wife."

This was not merely the second offense of Abraham after this manner, but it was just another outcropping of what had been a regular procedure by him and Sarah throughout the many years of their wanderings, as indicated by Genesis 20:13. The inference may easily be made that this device, wicked and sinful thought that it was, had been employed frequently, and that most of the times, they had found it to be effective. Certain special circumstances resulted in the utmost embarrassment to them, both in Egypt, and here. In fact, the most obvious reason why Abraham resorted to this subterfuge again would seem to lie in the fact that the special circumstances, present twenty years previously in the episode with Pharaoh, no longer prevailed. Sarah, at the time of this event was 90 years old, and her beauty had probably long since disappeared. The additional factor that led to the trouble here was most likely the intention of Abimelech to use the marriage device as a means of political and military strengthening of his little kingdom. The most practical way, according to the custom of the times, to unite himself with a powerful nomadic chieftain such as Abraham, was to marry into his family. Therefore, he sent and took Sarah. One may only marvel at the lack of discernment which can lead scholars to affirm this passage as a variant of the other episode, using such an argument as this: "Sarah is here conceived of as a young woman, capable of inspiring passion in the king."[6] There is absolutely nothing in this narrative that can justify such a remark!

"Abimelech ..." was a common Philistine designation, having significance, not as a personal name, but as a title used by Philistine kings. Incidentally, there are three ancient kingly titles that all have the same meaning:

Abimelech, meaning "Father-king," (Philistine), Padi-shah, meaning "Father-king," (Persian), Pharaoh, meaning "Father-king," (Egyptian).[7]

"God came to Abimelech in a dream ..." That such a thing as this occurred was made possible by Abimelech's believing in God, which did not seem be the case in the incident involving Pharaoh. God did two things at once to thwart any frustration of the divine plan for Abraham and Sarah:

1. he struck the royal household with a drastic illness that made the begetting of children impossible, in fact preventing sexual intercourse altogether, and
   
2. he alerted Abimelech to the divine prohibition against his touching Sarah.