Rule 1: 1. Passive and participles in narrative
A storyteller switches to the passive when the agent is nature, chance or simply unimportant, and uses participles after كَانَ or as predicates to set the scene. The jussive of the passive, لَمْ يُوجَدْ he was not found, and the negated participle, غَيْرُ مَوْجُودٍ not present, are both common.
كَانَ الرِّجَالُ ذَاهِبِينَ إِلَى وَلِيمَةٍ.
kāna r-rijālu dhāhibīna ilā walīmatin
The men were on their way to a feast.
Active participle, accusative sound plural, as predicate of كَانَ.
سَقَطَ فِي النَّهْرِ وَحُمِلَ بِالْمَاءِ.
saqaṭa fi n-nahri wa-ḥumila bi-l-māʾi
He fell into the river and was carried off by the water.
بُحِثَ عَنْهُ وَلَمْ يُوجَدْ.
buḥitha ʿanhu wa-lam yūjad
He was searched for and was not found.
Impersonal passive بُحِثَ عَنْ; passive jussive يُوجَدْ.
اَلْعَاشِرُ غَيْرُ مَوْجُودٍ، فَالْحِسَابُ عَلَى تِسْعَةٍ.
al-ʿāshiru ghayru mawjūdin, fa-l-ḥisābu ʿalā tisʿatin
The tenth is not present, so the bill is for nine.
غَيْرُ + genitive participle negates it.