Bereishit 22:1
Some time afterward, God put Abraham to the test. He said to him, “Abraham,” and he answered, “Here I am.”
Rashi
Here Am I: Such is the answer of the pious: it is an expression of meekness and readiness.
Midrash Tanchuma, Vayera 22
And He said unto him: “Abraham”; and he said: “Here am I.” What does the expression hineni (“here am I”) signify? It signifies meekness and piety. … the Holy One, blessed be He, said to Abraham: I have tried you nine times, and you underwent those trials successfully; now endure this final trial so that men may not say the earlier trials were of little consequence.
Nachmanides
…every test in the Torah is for the good of the one being tested.
Aidan Steinsaltz
Each of the trials of Abraham represents a different type of self-sacrifice. the trials are not about breaking the body or slaying the evil inclination. They are not about things that are intrinsically difficult to accomplish. The difficulty lies in the fact that self-sacrifice completely transcends the question of bodily limits; the challenge is to break the bounds of one’s self. In each of the trials, Abraham must prevail not over some external foe, but over himself.
…
Before facing the trial of love for his own child, Abraham was forced to ask, “Where is my whole world? Where is my whole concept of justice? Where is my morality?” At the Akeda, Abraham sacrifices not only his son’s body but his own soul.
Abraham’s trials present us with an opportunity to discuss self-sacrifice in our own lives. When is self-sacrifice required of us? What is the challenge of self-sacrifice in today’s world?
Bereishit 22:12
And he said, “Do not raise your hand against the boy, or do anything to him. For now I know that you fear God, since you have not withheld your son, your favored one, from Me.”
Rashi
FOR NOW I KNOW: R. Aba said: Abraham said to God, “I will lay my complaint before you. Yesterday you told me, “In Isaac shall seed be called to thee,” and then again you said, “Take now thy son.” Now you tell me, “Lay not thy hand upon the lad”! The Holy One blessed be He, said to him, in the words of Psalm 99:35, “My covenant will I not profane, nor alter that which is gone out of My lips.” When I told you, “Take thy son,” I was not altering that which went out from My lips, namely, My promise that you should have descendants through Isaac. I did not tell you “Slay him” but bring him up to the mountain. You have brought him up – take him down again.
Rabbi Leib, Alter of Ger, Sefer Emet
But in this case, it really wasn’t God’s will that he slaughter Isaac! Abraham’s heart [discerning this] felt no love or attachment to God in this act, since it was not God’s true will. That was the trial. And that is why it says, “He saw the place from afar” (vs. 4), meaning that he saw God was far from him [since this commandment was not really God’s will]. Now all he had was the fear of God, not to question him at all.
That is why Abraham insisted that God try him no more, that God never be far from him again. For Abraham’s path was that of love.