According to the Hanafi school it is Sunnah for circumcision to be performed for a new born as well as a person who accepts Islam. According to the other schools it is wajib. (Radd al-Muhtar v.7 p.342 Dar al-Fikr 1995)

Rasulullah (sallallahu alayhi wasallam) said: "The practices related to Fitrah (natural human ways) are five: Circumcision, shaving the pubic hair, trimming the moustache, pairing the nails and removing the hair of the armpits." - Sahih al-Bukhari

Rasulullah (sallallahu alayhi wasallam) said: "Circumcision is Sunnah for men and an honour for women" - Musnad Ahmad, Al-Bayhaqi

Rasulullah (sallallahu alayhi wasallam) also said: "Whoever accepts Islam should have his circumcision perfomed." - Talkhis al-Habir

In one hadith in Musnad Ahmad the words "get rid of the hair of disbelief and perform circumcision" have been recorded.

The practice of circumcision is one of the salient features (sha`a'ir) of the religion of Islam. It is from amongst those things that Rasulullah (sallallahu alayhi wasallam) encouraged his ummah to follow the way (millah) of Hadrat Ibrahim (alayhis salam) in. Hadrat Ibrahim (alayhis salam) was the first person to be circumcised at the age of 80. (Sahih al-Bukhari and Sahih Muslim)

Besides the above, circumcision also carries numerous physical benefits. It also prevents many illnesses.

Furthermore circumcision is an important aspect of taharah (cleanliness),which is so strongly emphasised in Islam, for when the foreskin is not removed, urine and other secretions can collect under the folded skin. This area can become the site of very painful infections from bacterial growth and the minor operation of circumcision greatly simplifies basic hygiene for men and boys. "Indeed God loves those who turn to Him constantly and He loves those who keep themselves pure" - Qur'an Surah al-Baqarah

Hence it is a greatly meritorious sunnah as well as physically beneficial to perform this act. However it is not a pre-requisite for conversion to Islam.

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai, www.ask-imam.com
FATWA DEPT.