Not all negative sentences take the same case ending.
«مَا زَيْدٌ قَائِمًا» has an accusative predicate.
«مَا زَيْدٌ إِلَّا قَائِمٌ» and «مَا إِنْ زَيْدٌ قَائِمٌ» have nominative predicates.
«مَا زَيْدٌ قَائِمٌ» is nominative in the Tamimi usage described by the source.
Negation of meaning and syntactic governance are separate issues.
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Common Error: Negation Does Not Fix Case
The Predicate of Mā and Lā Resembling Laysa
Not all negative sentences take the same case ending.
«مَا زَيْدٌ قَائِمًا» has an accusative predicate.
«مَا زَيْدٌ إِلَّا قَائِمٌ» and «مَا إِنْ زَيْدٌ قَائِمٌ» have nominative predicates.
«مَا زَيْدٌ قَائِمٌ» is nominative in the Tamimi usage described by the source.
Negation of meaning and syntactic governance are separate issues.