A clause used as a predicate normally requires a link (rābiṭ) to the primary subject. It may be supplied by an understood verbal subject, an overt pronoun, or another grammatically suitable connection.
زَيْدٌ قَامَ
Zayd stood up.
زَيْدٌ قَامَ أَبُوهُ
Zayd's father stood up.
In the first, the understood subject of the verb refers to Zayd. In the second, the suffix on «أبوه» refers to him while the action itself belongs to his father. These are clear instances of non-causal and causal clausal predicates.
The internal grammatical predication must be identified; not every element in a predicate clause attributes a property directly to the initial subject.