When parents circumcise their child they should greatly rejoice, and after the circumcision they should pray for the child, that he will have a holy soul and will be able to study and practice the Torah.

When one brings his son to circumcise him, a great joy will be awakened in his heart, and he shall glorify and praise God for granting him a son and the ability to bring him into the covenant of our patriarch Abraham…and he shall rejoice with a great joy in his heart, a spiritual joy which entails cleaving to Him, may He be blessed… and he shall pray to the Lord immediately after the circumcision that He will bestow upon the child a holy soul, [enabling him] to learn, to teach, to keep [the mitzvot], to perform, and to fulfill [the Torah and its commandments]. He shall bless the child, and let others bless him too. (Rabbi Yeshaya HaLevi Horowitz, Shenei Luĥot HaBerit, Ĥullin 43–44)

Rabbi Shalom of Belz was invited to celebrate a circumcision, and he said to the child’s father: “Today, your circumcision was completed.” The man asked in astonishment: “My circumcision?”

The tzadik explained: “Every mitzva must be fulfilled perfectly, in thought, speech, and act. We perform the act of circumcision on an infant, but he does not fulfill the thought aspect of the mitzva, as he does not yet possess understanding. Only when one brings his son into the covenant of our patriarch Abraham does he rectify the thought that was missing at his own circumcision.”