In the simple examples here, مَا and لَا can follow the case pattern of لَيْسَ.
- their ism is marfu, or occupies the position of raf if it is mabni
- their khabar is mansub
Compare the model: لَيْسَ زَيْدٌ طَوِيلًا. زَيْدٌ is the marfu ism; طَوِيلًا is the mansub khabar.
Do not assume that every occurrence of مَا or لَا has this function.