Genesis 16:11-12 “He will be a wild donkey of a man; his hand will be against everyone and everyone’s hand against him, and he will live in hostility toward all his brothers”.
Translation: Meaning because Ishmael having been not born “legit”, will respond in the most brutal way possible against the decendents of the “legit” born Issac.
PS: Ishamel was simply a b*****d because his mother was Hagar the slave.