I'm going to call cps on my friend's father
What makes you want to call CPS?
He beat him with his belt. My friend woke up with bruises on his buttocks.
Normally people don't like to interfere in other people's family but it is not good to stand by and let a friend be hurt. Even if they are upset that you interfere you can feel good that you helped your friend.
Child abuse is serious and I think the father deserves this. I'm sick of people telling me that I should do nothing.
You are doing the right thing by reporting abuse. You should not feel guilty or be silenced to stop your friend from being harmed.