If we are to follow your argument, circumcision becomes compulsory because it was practised by Abraham and even Moses before it was made compulsory by the torah.
Haddii ay ahayd in fariin siinayo ka timid xaga Ilaah, nebiyada kale sida Ibraahim iyo Muuse (NNKH) ayaa iyagoo daacad ah gudbiyey fariimihii loo soo dhiibay.