Praise be to Allah.
Allaah says of His slave and Close Friend (Khaleel) Ibraaheem (peace be upon him) (interpretation of the meaning):
And he said (after his rescue from the fire): “Verily, I am going to my Lord. He will guide me!”
“My Lord! Grant me (offspring) from the righteous.”
So We gave him the glad tidings of a forbearing boy.
And, when he (his son) was old enough to walk with him, he said: “O my son! I have seen in a dream that I am slaughtering you (offering you in sacrifice to Allaah). So look what you think!” He said: “O my father! Do that which you are commanded, In shaa’ Allaah (if Allaah wills), you shall find me of As-Saabiroon (the patient).”
Then, when they had both submitted themselves (to the Will of Allaah), and he had laid him prostrate on his forehead (or on the side of his forehead for slaughtering);
We called out to him: “O Ibraaheem!
You have fulfilled the dream!” Verily, thus do We reward the Muhsinoon (good-doers).
Verily, that indeed was a manifest trial.
And We ransomed him with a great sacrifice (i.e. a ram);
And We left for him (a goodly remembrance) among the later generations.
“Salaam (peace) be upon Ibraaheem!”
Thus indeed do We reward the Muhsinoon (good-doers).
Verily, he was one of Our believing slaves.
And We gave him the glad tidings of Ishaaq (Isaac) a Prophet from the righteous.
We blessed him and Ishaaq (Isaac). And of their progeny are (some) that do right, and some that plainly wrong themselves.” [al-Saaffaat 37:99-113)
Ibn Katheer (may Allaah have mercy on him) said: Allaah tells us that when His Close Friend (Khaleel) Ibraaheem migrated from the land of his people, he asked his Lord to grant him a righteous son, so Allaah gave him the glad tidings of a forbearing boy. This was Ismaa’eel (peace be upon him), because he was the first child who was born (to Ibraaheem, peace be upon him). There is no dispute on this point among the followers of the various religions [Jews, Christians and Muslims], that (Ismaa’eel) was the first child born to Ibraaheem.
“And, when he (his son) was old enough to walk with him” means, when he grew up and was able to take care of himself, like his father. Mujaahid said: “And, when he (his son) was old enough to walk with him” means, when he grew up and was able to ride and walk and work like his father did. When this happened, then Ibraaheem (peace be upon him) saw a dream in which he was commanded to sacrifice this son of his. According to a hadeeth narrated from Ibn ‘Abbaas and attributed to the Prophet (peace and blessings of Allaah be upon him): “The dreams of the Prophets are Wahy (revelation).” So Allaah was testing His Close Friend by commanding him to sacrifice this beloved son who had come to him in his old age, when he was very old, and after he had been commanded to settle the child and his mother in the desert, in a valley in which there was no noise, no people, no vegetation and no animals. So Ibraaheem obeyed the command of Allaah and left them there, putting his trust in Allaah, and Allaah sent them provision, from an unexpected source. After all that, when Ibraaheem was ordered to sacrifice this son of his, who was his firstborn and his only child, he responded to his Lord and obeyed His command, hastening to do as He willed. So he told his son about it so as to put him at ease and not sacrifice him by force.
“He said: ‘O my son! I have seen in a dream that I am slaughtering you (offering you in sacrifice to Allaah). So look what you think!’” The forbearing boy immediately responded: “He said: ‘O my father! Do that which you are commanded, In shaa’ Allaah (if Allaah wills), you shall find me of As-Saabiroon (the patient).’” This was the best answer he could give, an example of obedience to his father and to the Lord of mankind. Allaah said (interpretation of the meaning):
“Then, when they had both submitted themselves (to the Will of Allaah), and he had laid him prostrate on his forehead (or on the side of his forehead for slaughtering).” It was said that “when they had both submitted themselves” meant when they had both surrendered to the command of Allaah. “and he had laid him prostrate on his forehead” means that he put him face down. It was said that he wanted to slaughter him from behind so that he would not see his face at the time of slaughter. This was the view of Ibn ‘Abbaas, Mujaahid, Sa’eed ibn Jubayr, Qutaadah and al-Dahhaak… “They both submitted themselves” means that Ibraaheem said Bismillaahi’r-Rahmaan ir-Raheem and said Allaahu akbar and the boy said La ilaaha ill-Allaah because he was about to die. Al-Saddi and others said that (Ibraaheem) passed the knife over the boy’s throat but it did not cut him at all. It was said that a sheet of copper was placed between the knife and his throat, and Allaah knows best. Then it was called out from Allaah:
“’O Ibraaheem! You have fulfilled the dream!’” meaning, the purpose has been achieved, you have been tested and your obedience and willingness to do what your Lord commands have been proven. An alternative sacrifice will be provided instead of your son, just as you willingly submitted your body to the flames and you spent your wealth to honour your guests. Hence Allaah said:
“Verily, that indeed was a manifest trial” meaning that it was an obvious test.
“And We ransomed him with a great sacrifice” means, We provided a ransom for his son, an alternative to be sacrificed in his stead. According to the best known opinion of the majority of scholars, this was a fine white horned ram. Al-Thawri narrated from ‘Abd-Allaah ibn ‘Uthmaan ibn Khaytham from Sa’eed ibn Jubayr that Ibn ‘Abbaas said: It was a ram that had grazed in Paradise for forty years.
It was also narrated from Ibn ‘Abbaas that the dried ram’s head was still hanging on the downspout of the Ka’bah. This alone is evidence that the one who was to be sacrificed was Ismaa’eel, because he was the one who was settled in Makkah and we have never heard that Ishaaq ever came to Makkah from the time he was little. And Allaah knows best.
See Al-Bidaayah wa’l-Nihaayah by Ibn Katheer, 1/157-158
The one who was to be sacrificed was Ismaa’eel and not Ishaaq, because of the reasons stated above. In his Tafseer (commentary) on these Ayaat, Ibn Katheer also mentioned a number of points which prove that it was Ismaa’eel who was to be sacrificed. These points may be summed up as follows:
Ismaa’eel was the first child of whom glad tidings were given to Ibraaheem. He was older than Ishaaq according to the consensus of the Muslims and the People of the Book (Jews and Christians). According to the scriptures of the People of the Book, it was stated that Allaah commanded Ibraaheem to sacrifice his only son, and in some manuscripts it says that he was to sacrifice his first-born son.
The first son is usually more dear than other children, so the command to sacrifice him is a more exacting test.
It is mentioned that glad tidings of a forbearing boy were given, and that he was the one who was to be sacrificed. Later in the passage it says (interpretation of the meaning): “And We gave him the glad tidings of Ishaaq (Isaac) a Prophet from the righteous.” When the angels brought the glad tidings of Ishaaq to Ibraaheem, they said: “We give you glad tidings of a boy (son) possessing much knowledge and wisdom” [al-Hijr 15:53 – interpretation of the meaning].
Allâh said (interpretation of the meaning): “But We gave her glad tidings of Ishaaq, and after him, of Ya’qoob.” (Hood 11:71) meaning that a child called Ya’qoob would be born during their (Sara and Ishaaq’s) lifetimes, and he would have many descendents… and it does not sound right for Ibraaheem to be commanded to sacrifice him when he was little, because Allaah had promised that he would have many descendents.
Ismaa’eel is described here (in Soorat al-Saffaat) as being “forbearing” because this is very appropriate in this context.
Tafseer Ibn Katheer, 4/15. And Allaah knows best.