Who was the son whom Abraham was told to slaughter?

The Jews have always claimed that the dream in which Abraham received to slaughter his son was connected to Isaac and not Ishmael. However, both the Quran and the Torah indicate that the son was in fact Ishmael and not Isaac.

The Quranic evidence

1- There are six Quranic verses in which both Ishmael and Isaac are mentioned. In every one of the six verses Ishmael is mentioned first and Isaac second. This deliberate sequence confirms that Ishmael came before Isaac. The six verses are:

[2:133] Or were you witnesses when death came to Jacob, when he said to his children, "What will you wor
ship after I am gone?" They said, "We worship your God and the God of your fathers, Abraham, Ishmael and Isaac: One God, and to Him we are Submitters."

[2:136] Say, "We believe in God and in what was brought down to us, and in what was brought down to Abraham,
Ishmael, Isaac, Jacob and the Tribes, and in what was given to Moses and Jesus, and what was given to the prophets from their Lord. We do not distinguish between any of them, and to Him we are Submitters."

[2:140] Or do you say that Abraham,
Ishmael, Isaac, Jacob and the Tribes were Jewish or Christian? Say, "Are you more knowledgeable, or is God? Who is more transgressing than one who conceals a testimony he has from God? God is not unaware of what you do."

[3:84] Say, "We believe in God, and in what was brought down upon us, and in what was brought down upon Abraham,
Ishmael, Isaac, Jacob and the Tribes, and in what was given to Moses, Jesus and the prophets from their Lord. We do not distinguish between any of them, and to Him we are Submitters."

[4:163] We have inspired you as We inspired Noah and the prophets after him, and We inspired Abraham,
Ishmael, Isaac, Jacob and the Tribes, Jesus, Job, Jonah, Aaron, and Solomon, and We gave David the Psalms.

[14:39] Praise be to God for granting me, despite my old age,
Ishmael and Isaac. Indeed, my Lord is the Hearer of prayers.

2-
The words in 2:125 speak about a pledge which God took from Abraham and Ishmael. Isaac is not mentioned. This indicates that Isaac was either not born at that time, or that he was an infant and not yet old enough to give a pledge to God.

[2:125] And when We made the House a focal point for the people and a secure place: "Take Abraham's station as a prayer house." And We took a pledge from Abraham and Ishmael: "Purify My House for those who visit and those who retreat there for worship, and for those who bow and prostrate."

3-
The words in 2:125 speak about the building of "the House" which was built by Abraham and Ishmael. Once again Isaac is not mentioned. If Isaac was born, or old enough to contribute to the building of the House, he would have also been mentioned.

[2:127] And when Abraham was raising the foundations of the House, together with Ishmael: "Our Lord, accept this from us. You are the Hearer, the Knowledgeable.

4-
Finally, in Sura 37, and specifically the verses which narrate the dream of Abraham, we read the following sequence of events:

[37:100] My Lord, grant me of the righteous ones."
[37:101] So We gave him the good news of a forbearing boy.
[37:102] Then when he was old enough to accompany him, he said, "O my son, I see in a dream that I am slaughtering you, so see what you think." He said, "O my father, do as you are commanded to do. You will find me, God willing, of the patient ones."
[37:103] Then when they both submitted and he placed his forehead on the ground.
[37:104] We called him, "O Abraham,
[37:105] you have believed the vision!" Indeed, We thus reward the good doers.
[37:106] This was a clear test indeed.
[37:107] We made a concession for him in place of a grave slaughter.
[37:108] And We preserved his history for those who followed.
[37:109] Peace be upon Abraham.
[37:110] We thus reward the good doers.
[37:111] He was one of Our believing servants.
[37:112] And We gave him the good news of Isaac, a prophet from among the righteous.

The narration above tells us that God gave Abraham news of a forbearing boy (37:101), after which the event of the dream and the intended slaughter occurred. Then after God saved Abraham from slaughtering his son, God gave Abraham news about the coming of Isaac (37:112).
The sequence in this narration indicates that Isaac came after Abraham was given news of a forbearing boy and after Abraham saw the dream. This can only mean that the forbearing boy was Ishmael.

The Torah evidence

It is interesting to note that the Jews who insist that the son for the slaughter was Isaac, have sufficient indications in their own Book that it was Ishmael and not Isaac!

1- Abraham was 86 years when Ishmael was born (Genesis 16:16)

2- Abraham was 100 years old when Isaac was born (Genesis 21:5)

3- Therefore, Ishmael was 14 years older than Isaac.

4- We read that God commanded Abraham to sacrifice his "only son" (Genesis 22:2). Isaac was never an "only son", but for 14 years, Ishmael was the only son of Abraham.

5- To counteract this argument, the Jews manipulated the "only son" issue by claiming that Ishmael was an illegitimate son! They add that since Ishmael was an illegitimate son, then Isaac was the "only son".

6- Why did the Jews attempt to discredit Ishmael? Is it because prophet Muhammad and the Arabs are the seed of Ishmael and the Jews brand Muhammad a false prophet?

7- However, whoever attempts to corrupt God's truth will always fall flat on his face! In their blunder, they totally overlooked the fact that God acknowledged Ishmael to be the seed of Abraham and promised a great nation out of him.
I will make the son (Ishmael) of the slave woman into a nation also, because he is your own seed. (Genesis 21:13)

8- In response, they claim that Ishmael was indeed the seed of Abraham, but he was an illegitimate son because Hagar was not a legitimate wife of Abraham!

9- Once again their claim is refuted in their own Book. In Genesis 16:3 we read how Hagar was given to Abraham as a wife. How can the son of his own wife be illegitimate?

And Sarai Abram's wife took Hagar her maid the Egyptian, after Abram had dwelt ten years in the land
of Canaan, and gave her to her husband Abram to be his wife.
(Genesis 16:3)

10-
We also read in the Torah that Ishmael was given his name by God:

And the angel of the LORD said to her, "Behold, you are pregnant and shall bear a son. You shall call his name Ishmael, because the LORD has listened to your affliction."
(Genesis 16:11)

If we put the above evidence together, it becomes clear that Ishmael was the seed of Abraham, he was named by God and he was from the legitimate wife Hagar, how can Ishmael still be called illegitimate?