that what follows is rare in comparison to what precedes it, even if it is not rare in itself. This requires careful consideration. Then know that his statement: (and the exception occurs in affirmation) requires consideration, because the statement of the "Mughnī": the implication is in (yaqūm) not in (ʿasā), means: the implication is not in (ʿasā) at any time except in such and such. Thus, the estimated time is indefinite in the context of negation, so the exception after it is an exception from the negation, as in your saying: (Zayd does not come to us except on such and such a day). Yes, they may express it with something like your saying: (this is weak except if it is interpreted as such), so it is an exception that appears in affirmation, but in meaning it is a negation, because the meaning of weak is that it is not considered or not valid. And in the "Mughnī" it is stated at the beginning of the eighth chapter: (The sixth: the occurrence of the exception in affirmation, such as: (And indeed, it is difficult except for the humble) (al-Baqarah, 45) and (Allāh refuses except to perfect His light) (at-Tawbah, 32) [when the meaning is: and indeed, it is not easy except for the humble, and Allāh does not want except to perfect His light]. End of quote.