(Chapter 17—Verse 3 and following) And the Lord spoke to him, saying: Behold, my covenant is with you, and you shall be the father of a multitude of nations, and your name shall no longer be called Abram, but your name shall be Abraham, for I have made you the father of many nations. It should be noted that wherever we read Testament in Greek, in the Hebrew language it is the word covenant or pact, that is, Berith (). The Hebrews say that God, from his name, which is the Tetragrammaton among them, added the letter He to Abraham and Sarah: for he was first called Abram (), which means lofty father, and later he was called Abraham (), which means father of many: for what follows nations is not part of the name, but is understood. It is not surprising, therefore, that when it seems that the letter Α has been added among the Greeks and us: we have called it the Hebrew letter He added; for the language of that tongue is to write with He (ה), but to read with A (א): just as, on the contrary, the letter A is often pronounced as He.
Verse 7. "And the overseer of the eunuchs imposed names upon them, calling Daniel Belteshazzar (Balthasar), and Hananiah Shadrach, and Mishael Meshach, and Azariah Abednego." It was not only the overseer or master of the eunuchs (as others have rendered it, the "chief-eunuch") who changed the names of saints, but also Pharaoh called Joseph in Egypt Somtonphanec (Genesis 41:45), for neither of them wished them to have Jewish names in the land of captivity. Wherefore the prophet says in the Psalm: "How shall we sing the Lord's song in a strange land?" (Psalm 137:4). Furthermore the Lord Himself changes names benignly, and on the basis of events imposes names of special significance, so as to call Abram Abraham (Genesis 17:5), and Sarai Sarah (Genesis 17:15). Also in the Gospel, the former Simon received the name of Peter (Mark 3:16), and the sons of Zebedee are called "sons of thunder" (Mark 3:17) - which is not boanerges, as most people suppose, but is more correctly read benereem.
God said again to Abraham: And you shall therefore keep my covenant, you and your offspring after you throughout their generations; this is my covenant which you shall keep between me and you and your offspring after you: Every male among you shall be circumcised; and you shall circumcise the flesh of your foreskin, and it shall be a sign of the covenant between me and you. The Lord, in His kind provision, first established the covenant of His grace with the blessed Abraham and his offspring; and then He requires of them the covenant of obedience: so that the labor of striving might be less terrifying when the reward of perpetual remuneration is heard first. Therefore, the foreskin of the flesh is commanded to be circumcised, as a sign of the covenant between God and men, so that by this sign the faithful of that time might be reminded to cleanse themselves from all pollution of flesh and spirit, perfecting holiness in the fear of God; but also by a higher mystery, that carnal circumcision was done as a sign of the covenant between God and Abraham's offspring, because it was given as a sign of that covenant of which it was said above to Abraham: In you all the families of the earth shall be blessed; which no faithful person doubts pertains to the grace of the new testament. Therefore, in the sign of this covenant, no faithful person doubts that Abraham and his offspring were circumcised in the flesh of their foreskin, so that it might be typologically prefigured that one would be born from his seed who would cleanse his chosen ones from all stain of sins, and grant them perpetual blessing; to the sacrament of which cleansing aptly corresponds what follows:
[AD 420] Jerome on Genesis 17:3-14