Esau went to Ishmael and married Mahalath, the sister of Nebaioth and daughter of Abraham’s son Ishmael, in addition to the wives he already had.
KJV
Then went Esau unto Ishmael, and took unto the wives which he had Mahalath the daughter of Ishmael Abraham’s son, the sister of Nebajoth, to be his wife.
ASV
and Esau went unto Ishmael, and took, besides the wives that he had, Mahalath the daughter of Ishmael Abraham’s son, the sister of Nebaioth, to be his wife.