Is His saying, may He be exalted: "Tallah taftaʾu" a negation or an affirmation? And is it true that the answer to the oath with the imperfect verb has no "lam" of negation, and that affirmation comes with the "lam", such as: "Tallah lataftaʾu"?

The Almighty's saying: "تفتأ" (tafta'u) is negated by an unstated particle of negation, and the تقدير (taqdeer) [implied meaning] is: "لا تفتأ" (la tafta'u), meaning, "you will not cease remembering Yusuf." This was stated by Al-Khaleel, Sībawayh, Al-Farrā’, and Al-Naḥḥās. The exegetes and grammarians cited as evidence the saying of Imru' al-Qays: "So I said, by God, I will not cease sitting, Even if they sever my head and my limbs before you." Al-Alūsi mentioned that if an oath is not accompanied by the signs of affirmation (the letter lam and the nūn of emphasis), it indicates that it is negated, because negation does not accompany them. If affirmation were intended, it would have been said: "لتفتأن" (latafta'anna).