Judging the rhetorical appropriateness of Arabic expression draws on lexis, morphology, syntax, bayān, and familiarity with Arabic usage. Without morphology and grammar, the difference between active and passive forms or the identity of an agent may be missed; without context, nuances of expression remain obscure.
Morphology: the change from “أَرَادَ” to “أُرِيدَ”.
Syntax: “رَبُّهُمْ” as the agent.
Maʿānī: how the choice suits the situation.
Bayān: how meaning can be conveyed through different modes of signification.
Maʿānī goes beyond forming a correct sentence and asks why a particular form is better suited to the occasion.