ansible --private-key /PATH/TO/PRIVATE/KEY.KEY -i INVENTORY -m shell -a "whoami" all

test-web.example.com ansible_ssh_host=X.X.X.X ansible_ssh_user=MYUSER ansible_become_method=su ansible_become_user=root ansible_become_pass=Xjdt@mdaj12

[root@server ansi]# ansible --private-key /root/MASTER/audit/key.key -i test -m shell -a "whoami" all
test-web.example.com | SUCCESS | rc=0 >>
MYUSER

ansible all -b --private-key /root/MASTER/audit/key.key -i test -m shell -a "whoami"