Genesis 22:5

"Abraham," it says, "looking up saw the place from afar and said to his servants: sit here with the she-ass, but I and the boy will go as far as there, and when we have worshipped, we will return to you." He dismisses the servants. For the servants could not ascend with Abraham to the place of the burnt offering, which God had shown. "You," therefore, he says, "sit here, but I and the child will go; and when we have worshipped, we will return to you." Tell me, Abraham, do you truly say to the servants that you will worship and return with the child, or do you deceive? If you speak the truth, then you will not make him a burnt offering. If you deceive, it does not befit so great a patriarch to deceive. What state of mind, then, does this speech indicate in you? I speak the truth, he says, and I offer the boy as a burnt offering. For this reason I both carry the wood with me and return with him to you. For I believe, and this is my faith, that "God is able to raise him even from the dead."

Why is it said to the servants who prefigured the Jews, "Sit here with the ass"? Could that ass sit down, dearly beloved? It is said, "Sit with the ass," because the Jewish people who would not believe in Christ could not stand but, like the weak and languid sinner who had despised the staff of the cross, were about to fall to the ground. For this reason blessed Abraham said, "Sit here with the ass while the boy and I go on; and when we have worshiped, we shall come back to you." What is it that you are saying, blessed Abraham? You are going to sacrifice your son and you say you will return with him? If you offer him as a burnt offering, surely he will not be able to return with you. Blessed Abraham could reply: I speak the truth. I am offering my son, and I will return to you with him. So great is my faith that I believe that he who deigned to give him to me of a sterile mother could raise him from the dead. For this reason I say with truth, "When we have worshiped, we shall come back to you."

The two servants whom he ordered to stay with the ass typified the Jewish people, who could not ascend or reach the place of sacrifice because they would not believe in Christ. That ass signified the synagogue. The ram that was stuck among the briars with its horns also seems to represent the Lord, for Christ as it were stuck among thorns with horns when he hung on the beam of the cross, fastened with nails. When Isaac carried the wood for the sacrifice of himself, in this too he prefigured Christ our Lord, who carried his own cross to the place of his passion. Of this mystery much had already been foretold by the prophets: "And his government shall be upon his shoulders." Christ then had the government upon his shoulders when he carried his cross with wonderful humility. Not unfittingly does Christ's cross signify government: by it the devil is conquered and the whole world recalled to the knowledge and grace of Christ. Finally, the apostle also said this when he spoke of the Lord's passion: "He became obedient to death, even to death on a cross. Therefore God also has exalted him and has bestowed upon him the name that is above every name." We have said this, brothers, so that your charity may know that the government of Christ of which we read, "And the government shall be upon his shoulders," is none other than his cross. For this reason this lesson is read at Easter when the true Isaac, whose type the son of Abraham illustrated, is fastened to the gibbet of the cross for the human race.