Isaac's Birth and Ishmael's Expulsion

Twenty-five years after the first promise, Isaac is born — his name meaning "he laughs," the doubting laughter of chapters seventeen and eighteen now permanently converted into joy. But joy in this household carries a shadow. Sarah demands Hagar and Ishmael be sent away, and Abraham — grieved, because he loves this son too — obeys only after God instructs him to. What's worth noticing is what happens to Hagar and Ishmael once they're gone: God provides a well, and "God was with the lad." The same El Roi who found her at the spring in chapter sixteen is consistent here. The covenant line runs through Isaac — Paul will use exactly this distinction in Romans nine, "children of the promise" versus mere physical descent, as his working example for how election operates — but God's care for the excluded son doesn't stop because he's outside the covenant line. Ramose and Manganyi are right to press on this: the text refuses to let the chosen line's story be the only story God is attending to.