The sequence al-sabuʿu wāqifun is a nominal sentence after sudden-event idhā. The subject of kharajtu is the attached first-person pronoun, not al-sabuʿ.
Book example: خَرَجْتُ فَإِذَا السَّبُعُ وَاقِفٌ.
I went out and suddenly a wild beast was standing.
Kharajtu: perfect + subject suffix; fa: connective; idhā: sudden-event particle; al-sabuʿu: nominative subject; wāqifun: nominative predicate.
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Indeclinable Adverbs — Ghāyāt, Time and Place
The sequence al-sabuʿu wāqifun is a nominal sentence after sudden-event idhā. The subject of kharajtu is the attached first-person pronoun, not al-sabuʿ.
Book example: خَرَجْتُ فَإِذَا السَّبُعُ وَاقِفٌ.
I went out and suddenly a wild beast was standing.
Kharajtu: perfect + subject suffix; fa: connective; idhā: sudden-event particle; al-sabuʿu: nominative subject; wāqifun: nominative predicate.