Khitan (Arabic: ختان) or Khatna (Arabic: ختنة) are the Arabic term for circumcision, and the Islamic term for the recommended practice of male circumcision in Islamic culture. Male circumcision is widespread in the Muslim world, and accepted as an established practice by all Islamic schools of jurisprudence. There is no restriction in when should the circumcision be performed after birth; however, prophet Mohamed (peace and blessing be upon him) circumcised his grandsons Hassan and Husseins (RA) on the 7th days after they were born hence the 7th day after birth is the preferred time to get a circumcision from an Islamic perspective.
Christianity:–
According to the Gospel of Luke chapter 2, which states “And when eight days were fulfilled to circumcise the child, his name was called Jesus, the name called by the angel before he was conceived in the womb”
Judaism:-
The brit milah (Hebrew: בְּרִית מִילָה bərīṯ mīlā, “covenant of circumcision”; is a Jewish religious male circumcision ceremony. According to the Torah and Halakha (Jewish religious law), ritual circumcision of all male Jews and their slaves (Genesis 17:10–13) is a commandment from God that Jews are obligated to perform on the eighth day of birth, and is only postponed or abrogated in the case of threat to the life or health of the child.