«إلى ما هو له»
To that to which the action or its meaning belongs.
This does not require that the grammatical subject in every construction be the ultimate independent cause. Passive verbs and derived expressions attribute action-related meaning in different grammatical ways. The essential issue is which participant bears the predicated relation under the construction used.
In «ضَرَبَ زَيْدٌ عَمْرًا», Zayd performs the striking. In «ضُرِبَ عَمْرٌو», the passive reports the occurrence of striking upon ʿAmr. The ascription must be evaluated in light of the actual verbal form and its intended relation.