Puberty and Reason

As for puberty: Its opposite is childhood, and a child is not obligated to fast, nor is it required of him, but he is commanded to do so if he is able to. If he does it, the reward is for him, and if he does not, he owes nothing.
A person of unsound mind is not commanded to fast, and even if he fasts, it will not be accepted from him and it is not valid from him; because he is a person of unsound mind and has no intention.