The term 'Mother of Ishmael' is a reference to Hagar, the Biblical figure who was the mother of Ishmael, the son of Abraham and Sarah. Hagar was an Egyptian handmaid of Sarah, who gave her to Abraham as a wife after Sarah was unable to conceive. After Hagar became pregnant with Ishmael, Sarah became jealous and forced her out of the household. Hagar and Ishmael were then sent into the wilderness, where God provided for them.