The Talmud on Blessings for Circumcision

The sages taught [in a tosefta that] one who circumcises [a child] recites: Who has made us holy through His commandments, and commanded us concerning circumcision. The father of the [circumcised] child recites: Who has made us holy through His commandments, and commanded us to bring him into the covenant of Abraham, our father. Those standing [there] recite: Just as he has entered into the covenant, so may he enter into Torah, marriage, and good deeds.

And the one who recites the [additional] blessing says: Who made the beloved one holy from the womb, marked the decree in his flesh, and gave his descendants the seal and the sign of the holy covenant. Therefore, as a reward for this, the living God, our Portion, commanded to deliver the beloved of our flesh from destruction, for the sake of His covenant that He set in our flesh. Blessed are You, Lord, Who establishes the covenant.

One who circumcises converts says: Blessed are You, Lord, our God, King of the universe, Who made us holy with His commandments, and commanded us concerning circumcision. And the one who recites the [additional] blessing recites: Who has made us holy with His commandments, and commanded us to circumcise converts, and to drip from them covenantal blood, as were it not for the blood of the covenant, the heaven and earth would not be sustained, as it is stated: If My covenant would not be with day and night, the ordinances of heaven and earth I would not have placed (Jeremiah 33:25), [which is interpreted to mean that were it not for the covenant of circumcision that is manifest both day and night, the world would cease to exist. He concludes the blessing with the phrase:] Blessed are You, Lord, Who establishes the covenant.