In the biblical text of Genesis 16, Sarah (then Sarai) explicitly suggested that Abraham should take her Egyptian handmaid Hagar to produce an heir because she was barren.
However, after Hagar became pregnant, conflict arose, and Sarah later demanded that Abraham completely cast out Hagar and her son Ishmael to ensure Isaac remained the sole primary heir. From an Islamic perspective, the relationship is viewed with greater reverence, framing the journey of Abraham, Hagar, and Ishmael to the valley of Mecca as a fulfilled divine mandate rather than a simple domestic dispute.