تَاللَّهِ تَفْتَأُ تَذْكُرُ يُوسُفَ
By God, you will continue remembering Joseph. (Yusuf 12:85)
The oath and the sense of continuity indicate an understood negative particle before «تَفْتَأُ»: the underlying sense is «لا تفتأ», “you do not cease”.
The supplied particle is an explanatory reconstruction, not an alteration of Qur’anic wording. The verse remains quoted exactly, and its grammar and context account for the missing overt negative.