فمقتضى الحال هو الاعتبار المناسب للحال والمقام
The demand of the situation is the consideration appropriate to the circumstance and rhetorical station.
The decisive word is al-munasib, “appropriate.” Not every feature actually present in an utterance is demanded by the occasion. The demanded feature is one that appropriately serves the communicative aim.
An elaborate identification may be needless between close friends but essential in a formal legal setting. Omission and explicit mention can each be appropriate under different circumstances.