Fath al-Rabbani

Benefits: … There is a difference of opinion among the commentators regarding which son of Ibrahim alayhis salam was the one to be sacrificed: Isma'il alayhis salam or Ishaq alayhis salam? Ibn Jarir, Ibn Kathir, and most of the commentators have declared Isma'il alayhis salam to be the one intended for sacrifice, and this is the correct view. The reasons for its correctness are as follows:

(1) Study verses (100) to (113) of Surah as-Saffat. In these verses, both sons of Ibrahim alayhis salam are mentioned. Regarding the son who was to be sacrificed, Allah Ta'ala said: {فَبَشَّرْنَاہُ بِغُلٰمٍ حَلِیْمٍ} … So We gave Ibrahim the glad tidings of a forbearing boy. Then, up to verse (111), the incident of the sacrifice is described, and then it is said: {وَبَشَّرْنَاہُ بِاِسْحٰقَ نَبِیًّا مِّنَ الصَّالِحِیْنَ۔} … And We gave Ibrahim the glad tidings of Ishaq, a prophet from among the righteous.
From this sequence, it is clearly evident that the son who was to be sacrificed was Isma'il alayhis salam, who at that time was the only son of Ibrahim alayhis salam. Ishaq alayhis salam was born later.

The following excerpts are taken from Tafsir Ibn Kathir, with additional words used as needed:

(2) At that very time, the supplication was accepted and the glad tidings of a forbearing boy were given. This was Isma'il alayhis salam. He was older than your son Ishaq alayhis salam. Even the People of the Book acknowledge this; in fact, it is present in their books that at the birth of Isma'il alayhis salam, Ibrahim alayhis salam was eighty-six years old, and at the time of Ishaq alayhis salam's birth, he was ninety-nine years old.

(3) It is also in their book that Ibrahim was commanded to sacrifice his only son (and the only son could only be Isma'il alayhis salam, because he was the elder, and only the elder is considered the only one until a second son is born). But simply because the People of the Book themselves are from the descendants of Ishaq alayhis salam, and the Arabs are from the descendants of Isma'il alayhis salam, they altered the reality of the incident and transferred this virtue from Isma'il alayhis salam to Ishaq alayhis salam, and, making baseless interpretations, they altered the word of Allah and said: In our book, the word "waheed" is used, and by this is not meant "the only one," but rather "the one who is alone with you at that time." This is because Isma'il alayhis salam was with his mother in Makkah, and only Ishaq was with Khalilullah Ibrahim alayhis salam. But this is completely incorrect; "waheed" is only used for one who is the only child and has no brother.

(4) Furthermore, there is another point here: the love and affection that is generally shown to an only and firstborn child does not usually remain after the birth of other children. Therefore, the command to sacrifice the only child is a severe test and a difficult trial. This point applies only to Isma'il alayhis salam.

(5) The glad tidings of Isma'il are mentioned as a "forbearing boy," and then the mention of his being prepared for sacrifice in the way of Allah. After completing this entire account, then the glad tidings of the birth of the righteous prophet Ishaq are mentioned. And at the time of the glad tidings of Ishaq alayhis salam, the angels said: {غلام علیم} (And a person becomes knowledgeable when he grows up; this means that with the glad tidings of the birth of Ishaq alayhis salam, it was also indicated that he would live.)

(6) In another place in the Noble Qur'an, the glad tidings of Ishaq are given in these words: {فَبَشَّرْنَاہُ بِاِسْحٰقَ وَمِنْ وَّرَاء ِ اِسْحٰقَ یَعْقُوْبَ۔} … So We gave Ibrahim alayhis salam the glad tidings of Ishaq, and after Ishaq, the glad tidings of Ya'qub (Surah Hud: 71). From this, it is known that Ishaq alayhis salam would live and his progeny would continue, and from the descendants of Ishaq alayhis salam, Ya'qub alayhis salam would be born. Now, how could the one whose progeny was already foretold to continue be commanded to be sacrificed?

(7) The one intended for sacrifice (Dhabihullah) was Isma'il alayhis salam, because the place of sacrifice is Mina, and this location is in Makkah, and Isma'il alayhis salam was there. Ishaq alayhis salam was in the city of Canaan, which is in the region of Sham (Greater Syria).

(8) The Noble Prophet sallallahu alayhi wa sallam called Sayyiduna Uthman bin Talhah radi Allahu anhu and said: ((Inni kuntu ra'aytu qarnay al-kabsh hina dakhaltu al-bayt fa nasi'tu an amuraka an tukhamiruhuma fakhammirhuma, fa innahu la yanbaghi an yakuna fi al-bayt shay'un yushghilu al-musalli.)) Sufyan said: The two horns of the ram remained in the House until the House was burned, and they were burned as well. When I entered the House of Allah, I saw the two horns of the ram, then I forgot to order you to cover them, so now cover them, for it is not appropriate for anything to be in the House that distracts the worshipper. Sufyan says: The two horns of the ram remained in the House of Allah, and when the House was set on fire, they too were burned.
The ram that was brought as ransom for Isma'il alayhis salam—its horns were kept inside the structure of the Ka'bah. When, during the time of Yazid bin Mu'awiyah, after the incident of Harrah, the army of Banu Umayyah reached Makkah Mukarramah and besieged Abdullah bin Zubayr, and set up catapults and pelted the Ka'bah with stones, and due to the fire, the coverings of the House, the roof, and these two horns were burned. This incident occurred in Safar, 64 AH. (Buloogh al-Ma'ani min Asrar al-Fath al-Rabbani: 1/360)
This incident is also evidence that the one intended for sacrifice (Dhabihullah) was Isma'il, and for this reason, these horns continued to be passed down among his descendants, the Quraysh, until Allah Ta'ala sent Muhammad sallallahu alayhi wa sallam as a Prophet.
It is thus known that the son whom Allah Ta'ala commanded Ibrahim alayhis salam to sacrifice was Isma'il. And Allah knows best what is correct.