فَإِنْ كَانَ مُتَّصِلًا، وَقَعَ بَعْدَ «إِلَّا» فِي كَلَامٍ مُوجَبٍ
Translation: If the connected exception occurs after illā in an affirmative statement. (The author then prescribes the accusative.)
A connected exception after illā in a complete affirmative clause is accusative. The book also specifies the accusative in the disconnected and certain other arrangements.
«حَضَرَ الطُّلَّابُ إِلَّا خَالِدًا»
ḥaḍara: past verb; al-ṭullābu: nominative subject; Khālidan: accusative exception.
This is an added teaching example, not a book quotation.