Patristic Wisdom: Looking to the First Sunday in Lent

Then the Angel of the Lord called to Abraham a second time out of heaven, and said, “By Myself I have sworn, says the Lord, because you did this thing, and for My sake did not spare your beloved son, I will certainly bless you, and assuredly multiply your seed as the stars of heaven and as the sand on the seashore; and your seed shall inherit the cities of their enemies. In your seed all the nations of the earth shall be blessed, because you obeyed My voice.” (Genesis 22:15–18 LXX)

In the former promise there was only the statement; here an oath is interposed, which the holy Apostle writing to the Hebrews interprets in this way, saying: “God, meaning to show the heirs of the promise the immutability of his counsel, interposed an oath.” And again, Scripture says: “Men swear by one greater than themselves.” “But God, because he had no one greater by whom he might swear,” “ ‘I swear by myself,’ said the Lord.” It was not that necessity forced God to swear (for who would exact the oath from him?), but as the apostle Paul has interpreted it, that by this he might point out to his worshipers “the immutability of his counsel.” So also elsewhere it is said by the prophet: “The Lord has sworn nor will he repent: You are a priest forever according to the order of Melchizedek.”

At that time in the first promise there is no reason stated why the promise is given, only that he brought him forth and “showed him,” Scripture says, “the stars of heaven, and said: ‘So shall your seed be.’ ” But now he adds the reason on account of which he confirms with an oath the promise which will be steadfast. For he says: “Because you have done this thing and have not spared your son.” He shows, therefore, that because of the offering or passion of the son the promise is steadfast. This clearly points out that the promise remains steadfast because of the passion of Christ for the people of the gentiles “who are of the faith of Abraham.”

Origen, Homilies on Genesis 9.1