In Bereishit 17:13 we are commanded to circumcise all children born in our households and all servants bought for money, consequently Abraham performed it on Yishmael too. This is one reason why Muslim boys are circumcised even today.* Should a Muslim person ask it, can a mohel circumcise a person of Islamic faith? Can a Jewish person actively look for opportunities to do so by advertising for example?
* Although in Judaism it is debated, whether they can be considered descendants of Yishmael.