Apart from Christ's obedient sacrifice, probably the greatest act of faith in fear and trembling recorded in all of Scripture is the obedient response of Abraham when God commanded him to sacrifice his son Isaac.
"By faith Abraham, when he was tested, offered up Isaac, and he who had received the promises was in the act of offering up his only son, of whom it was said, 'Through Isaac shall your offspring be named.' He considered that God was able even to raise him from the dead, from which, figuratively speaking, he did receive him back" (Heb. 11:17–19).
This occurred after God had given Abraham a promise of future generations through Isaac and after God had made him wait many years for the birth of Isaac. In the interim, Abraham had taken steps to make sure that this promise was fulfilled with the aid of his wife Sarah, who, regarding herself as barren, offered her handmaid Hagar as a surrogate mother so that Abraham could have a son in order to fulfill the promise. Hagar had a son named Ishmael—but he was not the son of promise. Finally, after more years of waiting, God opened the womb of Sarah, and in her old age and in her barrenness, she brought forth a son who was given the name Isaac (when told she would have a son, Sarah had laughed, and the name Isaac means "laughter" in the Hebrew language). All of Abraham's hopes, his entire destiny, was wrapped up in this child.
Then God came to him and said, "Take your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the mountains of which I shall tell you" (Gen. 22:2). Abraham, in fear and trembling, set out on that three-day journey with Isaac. On the way, Isaac asked Abraham, "Behold, the fire and the wood, but where is the lamb for a burnt offering?" (v. 7). Abraham responded, "God will provide for himself the lamb" (v. 8).
I think we can read this story and make Abraham a paper saint with a glib kind of piety, as if he were saying to Isaac, "Hey, don't worry about it, son, God's going to provide us with a lamb when we get to the mountain." Not at all. Abraham was shaking in his boots. He was wondering: "How could God ask me to do this? How could God call me to such a place at such a time to do such a thing?" But he trusted God, clearly assuming that after he killed Isaac, God would raise him up from the dead (Heb. 11:19).
So Abraham went to the mountain designated by God, built the altar, spread the wood, and bound his son. But when he raised the knife, at the last possible second, God intervened and said, "Do not lay your hand on the boy or do anything to him, for now I know that you fear God" (Gen. 22:12). This is a story of faith to the absolute degree. The only thing that ever exceeds it in Scripture is the faith of Christ Himself.