Genèse 22:12

And He said, Stretch not out thy hand upon the young man, neither do him any evil; for now it is manifest before Me that thou fearest the Lord; neither hast thou withheld thy son the only begotten from Me.

FOR NOW I KNOW THAT THOU ART A G-D FEARING MAN. At the beginning Abraham’s fear of G-d was latent; it had not become actualized through such a great deed. But now it was known in actuality, and his merit was perfect, and his reward would be complete from the Eternal, the G-d of Israel.
The doctrine of this chapter which teaches that G-d is the One who tries Abraham and commands him about the binding of Isaac, and it is the angel of G-d who restrains and promises him, will be explained in the verse, The angel who hath redeemed me.

כי עתה ידעתי, I now can demonstrate My knowledge about you to the whole world,

כי ירא אלוקים אתה, that you are G’d fearing. [in the most selfless manner. Ed.]

עתה ידעתי, “now I, the angel, realise that G’d Who has elevated you Avraham as being on a loftier niveau than angels is justified.” This concept has been paraphrased by our sages in Sanhedrin 93 i.e. that “the righteous occupy a higher moral niveau than the ministering angels.”

ממני, “you are more G’d fearing than I am (the angel speaking). I was under the impression that as an angel I ought to possess more fear of the Lord than Avraham. G’d was aware that I was wrong. Now it has been demonstrated to me that Avraham was not only superior to me potentially, but that he has proven in actual fact.”

ויאמר...ואל תעש לו מאומה, again G’d repeated what He had said in different words, in order to lend additional emphasis to His warning not to touch Yitzchok.

כי עתה ידעתי, if we were to explain this word as derived from the root ידע in the kal conjugation and we follow the path we outlined in verse 1 that G’d wanted Avraham to translate his potential into an actual, in verse 1 of this chapter, the problem is that we never find the root ידע in a transitive mode; therefore I suggest that the meaning of ידעתי is similar to Exodus 33,12 ידעתיך בשם, or Exodus 33,17 ואדעך בשם. [This means כי שב החלק, “individual attributes form an integrated part of the larger pattern of one’s personality.” This is my understanding of the somewhat obscure phrase כי שב החלק, seeing that we do not have the author’s commentary on the verses in which he quotes himself as having interpreted the root ידע in such a fashion. Ed.] This allusion is sufficient for the initiated. (author’s words).

כי ירא אלוקים אתה. The word יראה, “fear,” mentioned here is none other than a form of אהבה, love, seeing that the fear was not something physical, concern for his body, but concern that he soul should not suffer irretrievable damage. Avraham was prepared to sacrifice his son to demonstrate that his love for abstract, invisible G’d was greater than his love for his physical, mortal son. He wanted to ensure that neither of them would forfeit their lives in the world to come.