The source distinguishes several associated elements. Seeing them together clarifies that the patient, agent, verbal noun, time, place, or cause may be given a predicate whose proper relation lies elsewhere.
RelationExpressionProper locus
Patientعِيشَةٌ رَاضِيَةٌThe person enjoying life is content
Agentسَيْلٌ مُفْعَمٌThe flood fills the valley
Verbal nounشِعْرٌ شَاعِرٌA poet composes poetry
Timeنَهَارُهُ صَائِمٌThe person fasts in daytime
Placeنَهْرٌ جَارٍWater runs in a river
Causeبَنَى الْأَمِيرُ الْمَدِينَةَWorkers perform construction
The relation and the contextual indication still need to be established in each particular use.