Abraham’s producing of Ishmael by the exercise of his natural strength was a serious offense against God and His economy. Because of this, after the birth of Ishmael, Abraham’s fellowship with God was broken; God waited for thirteen years (cf. Gen. 16:16), until Abraham’s natural strength was terminated, before He came to contact Abraham again (Rom. 4:19 and note Rom. 4:191a). See note Gen. 15:41.