In our liturgy, we repeatedly refer to the akeidas Yitzchak as testimony to Avraham's absolute trust in Hashem, and we plead to arouse Hashem's mercy upon us by virtue of our ancestor's great merit.
Some commentaries raise the question, Avraham's great devotion to Hashem notwithstanding, there have been many other instances of great sacrifice and martyrdom in our history. After all, Hashem spared Yitzchak's life, but Channah watched her seven sons be killed because of their refusal to bow to an idol. In fact, the king was so moved by Channah's children's acceptance of martyrdom that he wished to spare the life of the seventh child. He threw down his ring and said to the child, "Just bend down to pick it up. You will not be worshipping the idol, but the people will think you complied and bowed to the idol, and that will allow me to spare your life." Channah told the child not to pick up the ring, and the child was killed. Does this not equal the akeidah? Yet, we do not invoke Channah's merit in our prayers.
Unfortunately, there were far too many instances of martyrdom in our history, but the merit of the akeidah goes beyond martyrdom. In addition, the episode of the akeidah testifies to the greatness of Avraham in other ways, which constitute a source of teaching for us. These are subtleties in the episode of the akeidah that are often overlooked.
The Torah relates that on the day after he received the awesome Divine command, "Avraham woke up early in the morning" (Breishis 22:3) to carry out the divine command. The Talmud cites this as a virtue of Avraham and as a teaching that those who are diligent to serve Hashem hasten to fulfill His mitzvos. But one subtlety is overlooked. If Abraham awoke in the morning, obviously he slept during the night! What father, knowing that he was to sacrifice his beloved child the next day could possibly sleep peacefully? At the very best, a father would be up at night, pacing the floor, wringing his hands and crying. But not Avraham. His trust in Hashem was so perfect that he took everything with equanimity. Everything that Hashem does is good. If Hashem wants me to have a son, that is good. If Hashem wants me not to have a son, that, too, is good. Avraham slept peacefully all night.
Another great virtue of Avraham is pointed out by Harav Chaim Shmuelevitz (Sichos Mussar 5731:1 ). For decades, Avraham had been denouncing idol worship. The idolatry most severely condemned in the Torah is the Molach, which was served by human sacrifice. Avraham vigorously condemned this practice, saying that it was unthinkable that G-d would ask for human sacrifice. Now, if he would carry out what he felt to be the Divine command to sacrifice Yitzchak, what will he say to the multitude whose practice of human sacrifice he had so vehemently condemned? He would have to say, "You were all right. Throughout my entire lifetime, I was wrong!" Few people can admit that the position which they espoused so vigorously and for so many decades was an error. The greatness of Avraham was that he was ready to do this.
We can see now why the akeidah is singled out as Avraham's greatest merit. It tells us much about the character of the father of our nation, whom we are to emulate.