Rajulun ibnu Zaydin illustrates that the first noun is a common indefinite noun rather than a proper name; the special patronymic omission does not apply.
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If the First Noun Is Not a Name
Tanwīn: Five Types, Their Function, and Omission
Rajulun ibnu Zaydin illustrates that the first noun is a common indefinite noun rather than a proper name; the special patronymic omission does not apply.