With mā kāffa, Zaydun may be nominative as an ordinary subject of a nominal clause; not Zaydan as an inna-subject.
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Nominal Sentence after Innamā
Inna and Its Sisters: Six Particles, Meanings, Government and Exceptions
With mā kāffa, Zaydun may be nominative as an ordinary subject of a nominal clause; not Zaydan as an inna-subject.