Midrash su Ezechiele 27:21

Again after three years Abraham went to see his son Ishmael, having sworn to Sarah as on the first occasion that he would not descend from the camel in the place where Ishmael dwelt. He came there at midday, and found there Ishmael's wife. He said to her: Where is Ishmael? She replied to him: He has gone with his mother to feed the camels in the desert. He said to her: Give me a little bread and water, for my soul is faint after the journey of the desert. She fetched it and gave it to him. Abraham arose and prayed before the Holy One, blessed be He, for his son, and (thereupon) Ishmael's house was filled with all good things of the various blessings. When Ishmael came (home) his wife told him what had happened, and Ishmael knew that his father's love was still extended to him, as it is said, || "Like as a father pitieth his sons" (Ps. 103:13). After the death of Sarah, Abraham again took (Hagar) his divorced (wife), as it is said, "And Abraham again took a wife, and her name was Keturah" (Gen. 25:1). Why does it say "And he again"? Because on the first occasion she was his wife, and he again betook himself to her. Her name was Keturah, because she was perfumed with all kinds of scents.