God told Abraham that all the males must be circumcised as part of that agreement

9 Then God said to Abraham, “Now you must obey your part of the agreement that I am making with you, and your descendants must also obey it, for all generations. 10 This is the agreement that I am making, between myself and you and all your descendants: Every male among you must be circumcised. 11 ◄Cutting the foreskins of/Circumcising► them will be the sign that you have accepted the agreement I am making with you. 12 Every male child among you must be circumcised when he is eight days old, in all future generations. That includes baby boys in your household or those born from slaves that have been bought, and baby boys of foreigners who live among you but do not belong to your household. 13 It does not matter whether their parents are members of your household or slaves that have been bought; they must all be circumcised. Your bodies will have this mark to show you have accepted this everlasting agreement I am making. 14 You must expel from your community any male who has not been circumcised, because by not being circumcised that person has disobeyed my agreement.”