Genesis 26:9

And Abimelech called Isaac,.... Sent a messenger to desire him to come to him:

and said, behold, of a surety she [is] thy wife: and then perhaps told him of what he had observed that passed between them; which was a clear proof that they must be man and wife, or he would never have took such liberties with her:

and how saidst thou, she [is] my sister? what reason hadst thou for it? what could induce thee to say so?

and Isaac said unto him; not alleging, as Abraham did, any relation that was between them before marriage:

because I said; that is, within himself, for, he did not speak it out to others:

lest I die for her; for her sake, that another might have and enjoy her; it was fear of losing his life that led him to take such a step, and give out that she was his sister.