As regarding the fast by permission...

As regarding the fast by permission, a woman cannot fast an optional fast without the permission of her husband; a slave may not observe an optional fast without the permission of his master; and a guest may not fast an optional fast except with the permission of his host; the Messenger of Allah (S) has said, ‘Whoever visits some folks, he should not observe an optional fast except with their permission.' As regarding disciplinary fast, a boy reaching adolescence is ordered to fast when he reaches the age of…