Basemath (Ishmael's daughter)
Basemath was one of Esau's wives and the mother of Reuel. She was a daughter of Ishmael. Prior to marrying Basemath, Esau married at least two Hittite wives. Esau's parents, the prophet Isaac and Rebekah, disapproved of Esau's Hittite wives.
Esau overheard Isaac task Jacob with finding a proper wife for himself, and Esau realized that his Hittite wives offended his parents, so Esau married Mahalath, an Ishmaelite. Since the Ishmaelites were descendants of Abraham, they were more acceptable to his parents.
Some believe that Basemath to be the same person as Mahalath. If, on the other hand, Basemath is a separate individual from Mahalath, then Esau presumably married Basemath for the same reasons he married Mahalath.