These are the names of Ishmael’s sons; their names according to the family records are: Nebaioth, Ishmael’s firstborn, then Kedar, Adbeel, Mibsam,

so Esau went to Ishmael and married, in addition to his other wives, Mahalath daughter of Ishmael, Abraham’s son. She was the sister of Nebaioth.

and Basemath daughter of Ishmael and sister of Nebaioth.