Rashi on Genesis 20:2/רש"י על בראשית כ׳:ב׳

1ויאמר אברהם AND ABRAHAM SAID — This time he did not ask her consent but forcibly and against her inclination he stated that she was his sister, because she had already been taken once to Pharaoh’s house on account of this (Genesis Rabbah 52:4).

2אל שרה אשתו OF SARAH HIS WIFE — means in reference to (אֶל in sense of עַל) just as (1 Samuel 4:21) “in reference to (אל) the ark of God being taken, and in reference to (אל) her father-in-law”, where the word אל, in both cases, has the same meaning as על.