Suppose someone makes a promise to Allah (swt) not to sleep for 3 days as a punishment for a sin and ask Allah (swt) not to forgive him if he break it. While he tried not to sleep, he could not control it, what is the penalty, or can Allah (swt) still forgive the person?
That's very weird!
But I think this promise is not allowed and does not include any punishment.
Because human beings are not allowed to hurt themselves. It's analogous to promising Allah to cut your legs! Is it possible that Allah accepts that and wants you to cut your legs or consider any punishment for you?