Genesis 20:12, “Besides, she is indeed my sister, the daughter of my father though not the daughter of my mother, and she became my wife.” ESV

“Abraham speaks of Sarah as his half-sister. The common Jewish tradition referred to by Josephus (Antiquities I, vi 6) and also by Jerome is that Sarah is another name for Iscah (Genesis 11:29), the daughter of Haran and sister of Lot, who is called Abraham’s ‘kinsmen,’ signifying ‘relative.’ (Genesis 13:8).” ESV Hebrew-Greek Key Word Study Bible Notes