Here is, I. The promise made to Abraham of a son by Sarai , that son in whom the promise made to him should be fulfilled, that he should be the father of many nations; for she also shall be a mother of nations, and kings of people shall be of her , Gen. 17:16. Note, 1. God reveals the purposes of his good-will to his people by degrees. God had told Abraham long before that he should have a son, bu...