Genesis 25:21 (WEB) Isaac entreated Yahweh for his wife, because she was barren. Yahweh was entreated by him, and Rebekah his wife conceived. 22 The children struggled together within her. She said, “If it is so, why do I live?” She went to inquire of Yahweh. 23 Yahweh said to her, “Two nations are in your womb. Two peoples will be separated from your body. The one people will be stronger than the other people. The elder will serve the younger.”

James 5:16b (WEB) The insistent prayer of a righteous person is powerfully effective.