Is excepting a part from what has been affirmed (Istithna') permissible?

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Excepting a portion from what has been affirmed is permissible without known disagreement. This practice is established in the language of the Arabs, the Quran, and the Sunnah. Evidence includes the Quranic verse stating the stay was for a thousand years except fifty years (Quran 29:14), and the command for all angels to prostrate except Iblis (Quran 15:30-31). Furthermore, the Prophet, peace be upon him, stated regarding the martyr that all their sins are expiated except debt. When one affirms something and makes an exception, they are affirming the remainder after the exception. For instance, if one admits liability for one hundred except ten, they admit to ninety, as the exception prevents the excepted amount from being included in the affirmation.