Say, I pray thee, thou art my sister: that it may be well with me for thy sake; and my soul
shall live because of thee.
Abram makes his wife lie for him, by telling the Egyptians that she is his sister. But at least it was half-true, since
she was his half-sister. Such incestuous marriages are condemned elsewhere in the
Bible, but god makes an exception for Abram and Sarai. (See Gen.17:15-16
where God blesses their marriage.)