رَجُلٌ كَرِيمٌ أَبُوهُ
A man whose father is generous.
«كريم» is morphologically an adjective, so a superficial analysis might call it merely a single predicate and ignore linkage. Yet the generosity concerns «أبوه». Thus being a single lexical expression and being non-causally attributed are not identical.
Grammatically the adjective is linked to the father's quality; semantically it is the father, not the named man, whose generosity is stated. This is why the source rule insists on a separate condition for absence of causal linkage.