In Chayei Sarah, before recording Abraham’s passing, the Torah informs us that he remarried — apparently to his third wife after Sarah and Hagar, a woman called Keturah.
But Rashi quotes a Midrash that declares Keturah and Hagar as one-and-the-same person, which means that Abraham had many more children with Hagar besides for Yishmael.
Nevertheless, other commentaries dispute this proposal, noting that the text clearly indicates Keturah could not possibly have been Hagar.
Rabbi Dunner gathers together all the sources to present a range of opinions, and then presents a startling Netivot Shalom, which offers a kabbalistic understanding of this unusual biblical narrative.