John Calvin on Genesis 12:18-19

18. And Pharaoh called Abram . Pharaoh justly expostulates with Abram, who was chiefly in fault. No answer on the part of Abram is here recorded; and perhaps he assented to the just and true reprehension. It is, however, possible that the exculpation was omitted by Moses; whose design was to give an example of the Divine providence in preserving Abram, and vindicating his marriage relation. But, although Abram knew that he was suffering the due punishment of his folly, or of his unreasonable caution; He, nevertheless, relapsed, as we shall see in its proper place, a second time into the same fault.