There is something interesting about Ishmael and his modern day descendants, the Palestinians, Muslim, and Arabs.
Genesis 16 says "He shall be a wild man and his hand shall be against every man."
There is an aggressive fighting in the descendants of Ishmael that we see today as they fight Israel and much of the world.
Even though Sarah and Abraham came up with a human plan to fulfill God's promise, God was still faithful to them.
........Read Genesis 17:15-21