and do righteous deeds, and counsel one another to truth, and counsel one another to patience.” (al-ʿAṣr 103:3)

By our phrase “through illā or one of its sisters” we deliberately excluded specification made by a condition and the like.

Conditions for a valid exception
For an istithnāʾ to be sound, several conditions must be met, among them:
1 – It must be contiguous with the statement from which the exception is taken, either in reality or by legal convention.
Actual contiguity is when the exception follows the general statement immediately, with nothing in between. Constructive contiguity is where the only break is something unavoidable, such as coughing or sneezing.
If the interruption could have been avoided, or if the speaker falls silent, the exception is invalid. For instance, if someone says, “My slaves are free,” then pauses, or turns to other speech and afterwards says, “…except Saʿīd,” the exception is null and all of them are emancipated.
Another opinion holds that the exception remains valid despite a pause or other break, provided it is still part of the same discourse. The evidence is the ḥadīth of Ibn ʿAbbās (may Allah be pleased with both of them): on the day Mecca was conquered, the Prophet ﷺ declared, “Indeed, Allah sanctified this town the day He created the heavens and the earth; its thorny plants are not to be cut, nor its wild vegetation uprooted.” Al-ʿAbbās said, “Messenger of Allah, except for the idhkhir, for we use it in our gold-smithing and our houses.” He replied, “Except for the idhkhir.”(1) This opinion is stronger because this ḥadīth substantiates it.