Комментарий к Берешит 17:27

נמולו אתו, by Avraham. The root of both נמול and נמולו is the verb נמל.

וכל אנשי ביתו, “and all the males of his household;” where the previous verse had spoken only of Avraham, this one speaks of all the members of his household. This included slaves purchased by him, not born to members of his household, as well as anyone belonging to Yishmael.

נמולו אתו, it does not say: מלו אתו, which would have implied that they were circumcised against their will, but they were all willing participants in this procedure.