Is it illegal to use my friends EBT/Food stamps card?

My friend is in prison and he left his EBT card at my house when he left, when we talked on the phone the other day he gave me his pin number. The card is still collecting money every month and has $600 on it, which seems to be the limit. My dad says that it is illegal for me to use it even if he gave me the pin number. Is he right or not? And why would it be illegal? I have been given someones EBT card to go to the store and pick up groceries before, so does him being incarcerated have anything to do with it? IDK. Please help?