This is an effective weapon against the Devil the father of lies who tries to sow the seed of doubts in the heart of believers that there is no prophet in the line of Ishmael the Hebrew.
Ishmael is never a Muslim as he did not worship Allah of Muhammad but YHWH Elohim of Abraham only. Ishmael married an Egyptian wife from Egypt and dwelled in Paran near Egypt; Egyptians are likely the descendants of Ishmael and Esau through intermarriage who were so advanced in the knowledge of construction of pyramids and cuneiforms.
Genesis 28:9 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.
First of all, let me quote from RNKJV Genesis 21:8-21 as below:
21:8 And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned.
21:9 And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking.
21:10 Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.
21:11 And the thing was very grievous in Abraham's sight because of his son.
21:12 And Elohim said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.
21:13 And also of the son of the bondwoman will I make a nation, because he is thy seed.
21:14 And Abraham rose up early in the morning, and took bread, and a bottle of water, and gave it unto Hagar, putting it on her shoulder, and the child, and sent her away: and she departed, and wandered in the wilderness of Beer-sheba.
21:15 And the water was spent in the bottle, and she cast the child under one of the shrubs.
21:16 And she went, and sat her down over against him a good way off, as it were a bowshot: for she said, Let me not see the death of the child. And she sat over against him, and lift up her voice, and wept.
21:17 And Elohim heard the voice of the lad; and the angel of Elohim called Hagar out of heaven, and said unto her, What aileth thee, Hagar? fear not; for Elohim hath heard the voice of the lad where he is.
21:18 Arise, lift up the lad, and hold him in thine hand; for I will make him a great nation.
21:19 And Elohim opened her eyes, and she saw a well of water; and she went, and filled the bottle with water, and gave the lad drink.
21:20 And Elohim was with the lad; and he grew, and dwelt in the wilderness, and became an archer.
21:21 And he dwelt in the wilderness of Paran: and his mother took him a wife out of the land of Egypt.
1) Under the Jewish culture, a child has weaned when he reaches about 2 or 3 years old. As Ishmael was born when Abraham was 86 years old and Isaac was born when Abraham was 100 years old, Ishmael was 14 years older than Isaac. When Isaac has weaned, Ishmael is about 16 years old no longer a little child. At the time of Abraham who lived around 2000BC, by the age of 16 it is already of marriageable age and capable to start a new family of his own. Gen 21:21 shows that Ishmael the Hebrew intermarried an Egyptian wife of the same race as his mother.
2) Sarah had instructed Abraham to cast out Ishmael and Hagar because she did not want Ishmael to co-inherit with Isaac and his seed vide Gen 21:10. Sarah was a free woman whereas Hagar was a slave woman. YHWH El has chosen Sarah to bear the child of promise as His perogative.
3) Abraham was acting upon the demand by his wife Sarah and prior approval from YHWH vide Gen 21:12 to make the most painful decision in his life for disowning his firstborn child Ishmael.
4) The idiom of "cast out" means divorce for Hagar and "severance of firstborn son" for Ishmael. During Abraham's culture such act of expulsion of wife and son is understood as total severance of relationship. Abraham understood the idiom vide Gen 21:11 which means an excommunication of his firstborn son.
5) The firstborn rights of Ishmael was revoked by Abraham at the approval of YHWH. Though Ishmael was promise to be made a great nation, there is no covenant of YHWH that He would be their Elohim. This is proven by 2K years of silence in respect of No Prophethood for the sons of Ishmael as it goes only with lineage of Isaac until Messiah Yah'sua.
6) There is no prophecy of YHWH about a forthcoming prophet made in the Old Testament who is yet to come after Messiah Yahshua. It was made clear by Yahshua in Matthew 11:13 that "all prophets and the law Prophesied until JOHN" which has set the time-limit to Yahshua Himself who came to minister at the time of John the Baptist.
7) The historical and scriptural records show that ISRAEL today is the Nation with lineage of prophethood from Abraham, Isaac and Jacob till John the Baptist whereas there is no lineage of prophethood from Ishmael until today.
8) By understanding the implication of casting out of Abraham's family in respect of Hagar and Ishmael, any false claim of prophethood by the sons of Ishmael can be easily identified as liars and sons of the father of lies the Devil vide John 8:44.
9) Ishmael and Isaac were presented to bury Abraham when he died but there is no record of Ishmael inheriting anything from Abraham. The nation of Israel is a witness that Israelites are the benefectors while Ishmaelites are the mockers just like Ishmael mocking Isaac on the day he weaned.
What I have overlooked before is that Ishmael the Hebrew is the victim of circumstances. But after thorough research on this incident of Ishmael's expulsion from Abraham's family, it is clear that Ishmael was actually disowned and not only a matter of separation in order to avoid the family conflict.
There is another version from disbelievers that Abraham still regularly visited Ishmael and Hagar after the expulsion. I would say it is a blatant lie of Satan the father of lies as the context of the scriptural on "sent her away" vide Gen 21:14 means Abraham did not accompany Hagar at all.
This paragraph is just a speculation as it is not found in the Holy Bible - not an absolute truth: Even if Abraham may have visited Hagar and Ishmael secretly without Sarah's knowledge, it is merely a personal concern and not an approval from YHWH. Abraham did not plead with YHWH to reinstate the inheritorship of Ishmael. Gen 21:12 is clear that YHWH had appointed ISAAC to be his prophet rather than Ishmael. Even before Isaac was conceived, Abraham had proposed to YHWH as his inheritor but YHWH said ISSAC would be born in the following year to him.
It was Ishmael's own action which triggered Sarah to act against him. Sarah had treated Hagar harshly when Hagar despised her mistress. Ishmael suffered the consequence of his own fault. Abraham was not harsh to disown Ishmael as it was YHWH's will for him to do so for the benefit of ISAAC. The holy blood of Israel was preserved by excommunicating Ishmael lest the sons of Ishmael would practise intermarriage with the tribe of Judah and no holy race would be preserved. Messiah Yahshua was the King of the Jews - holy nation of Israel.
Hagar did not suffer any loss as she became a free woman after the expulsion. Ishmael was old enough to get married and started his own family in a few years time. As the marriage law says a man shall leave his father and mother and be united with his wife as one flesh, Ishmael through his marriage with an Egyptian woman has proved that he has reached his manhood.
Ishmael was an archer and was never a prophet. Just as Esau the firstborn son did not inherit the prophethood from Isaac, Ishmael did not inherit the prophethood from Abraham. What we see today is Arabs making false claim that they are descendants of Ishmael and demanding Jerusalem City to be co-inheritors.
Although Arabs did come from the sons of Abraham through his concubine Keturah there is no proof that Muhammad came from the lineage of Ishmael. What we see today in the Middle East was arising from the family conflict of Abraham about 4000 years ago. Leaving aside the religious issue, the peace plan for Israel and Palestinian State may work out. But we see Satan is trying to create disorder and chaos at Jerusalem City a symbolic for New Jerusalem City.
This main objective is to eliminate all false claim of prophethood from the lineage of Abraham through Ishmael except through ISAAC only through whom Messiah Yahshua came forth as the promised Saviour of the whole world.
YHWH by pictograph of ancient Hebrew has decoded it to mean:
"Behold the hand, behold the nail"
which in context refers to the words of Messiah Yahshua "Behold my hands" when He spoke to doubting Thomas about His nail wound in his Hands. Google for "Behold the hand, behold the nail" for more details.
For true believers in YHWH and Yah'shua, it is a blessing from YHWH that you can see that the plan of YHWH can be unfolded for a period of 4,000 years from Abraham till today.