One motive for preposing is hastening good or bad emotional impact. A name or description at the start may make the listener anticipate gladness or anxiety even before the predicate is completed.
«سعد في دارك»
Saʿd is in your house.
«السفاح في دار صديقك»
The bloodshedder is in your friend's house.
The identity in initial position creates an emotional frame for what follows. The classical discussion also mentions favorable and unfavorable omens as discourse associations; describing their rhetorical use does not establish the truth of superstitious beliefs.