[2:131] When his Lord said to him, 'Submit', he said, 'I have submitted to the Lord of the Worlds'.
Islām is sincerity (ikhlāṣ) and submission (istislām). Its true meaning is withdrawing entirely from the states of mortal humanity (bashariyya) with respect to the struggles over free choice (ikhtiyār) and the oppositional tendencies of the lower self (muʿāra?āt al-nafs). [Abraham] said, 'I have submitted to the Lord of the Worlds: I have accepted the command (amr), hearing and obeying, and I have embraced the decree (ḥukm) as much as I am able'. He did not hold back any of his wealth, body or progeny. When he was commanded to sacrifice his son, he intended to do it. When He said to him, 'Release him from his bond', he did what he was commanded to do. There was no free choice in either of the states for him and no self-directing (tadbīr).
It is said his saying, 'I have submitted (aslamtu)' was surely not by way of any claim for himself because the true meaning of islām is rather to absolve oneself of strength and power. So when He said, 'I have submitted', it was as if he said, 'Raise me up in what you have charged me and carry out from me that to which you have commanded me'. He turned the affair over to Him without proclaiming any meaning or warrant from himself.
It is said He bid him to take on the demands of the divine power of deliberation (mu?ālabāt al-qudra), for surely one who takes up his abode in friendship, what dwells in him is what dwells in the other (fa-inna man ḥalla fī'l-khullati maḥallahu yaḥullu bihi lā maḥāla mā ḥalla bihi).
One might ask a question here: How could Abraham (ṣa) have said, 'I have submitted', when it was said to our Prophet (ṣ), 'Know', but he did not say, 'I have come to know?' The answer for that has several aspects, one of which is that the Prophet (ṣ) said, 'I am the most knowledgeable of you about God' but since a law did not come after him it used to be said about him that he said, 'I have come to know' (ʿalimtu).
It is said God (s) spoke about the Messenger (ʿa) in His saying, 'The Messenger believes' [2:285], because belief is knowledge of God (swt). The words of the Real and the information He gave about him is more perfect then his (ʿa) giving information from himself [as Abraham did].
Another aspect is that when Abraham spoke, saying 'I have submitted', he was subjected to the trial, whereas our Prophet (ṣ) was wary of anything that could take the form of a claim, and so he was protected and spared.
Another aspect is that Abraham (ʿa) was commanded to follow a course of actions that indicate submission to Him, whereas our Prophet (ṣ) was commanded to know. The shares of submission (islām) are limited while the subtleties of knowledge are not.