Musar su Genesi 22:21

The truth is that this test was due to Ishmael's and Isaac's dialogue, a competition who could serve the Lord better. Such a dialogue certainly reflected the "right" side of the emanations. Rabbi Yossi the Galilean describes the matter in Bereshit Rabbah 55,5 when he says that the words והאלוקים נסה את אברהם must be understood as "G–d placed Abraham on a high mast, like that on a ship." His meaning is that G–d simply wanted to demonstrate to the whole world the devotion of an Abraham to the most difficult demand G–d could make upon him. Nonetheless, there is no denying that Abraham had found a detractor in Satan, and we have it on the authority of the Zohar that any accusation leaves some impression that G–d has to address Himself to, even if He does not do so immediately. In such a situation G–d hands someone else to Satan as a ransom, as alluded to in Isaiah 43,4: ואתן אדם תחתיך, "I give men in exchange for you." Abraham was afraid that the effect of Satan's accusation against him might have negative effects on Isaac's descendants. This is why G–d told him immediately after the binding of Isaac (Genesis 22,21) that the ransom had already been assigned to Satan: עוץ בכורו, "Utz the first born of Nachor," otherwise known as job, as we know from Job 1,1 "there lived a man in the land of Utz, Job was his name." We know that G–d delivered the fate of this man into the hands of Satan (ibid.). The mechanics of how this ransom works are discussed at length in the Zohar.