How can one reconcile Al-Dahhak's statement, "Every 'dhann' (conjecture/assumption) in the Qur’an from a believer is certainty, and from a disbeliever is doubt," with the interpretation of "فَظَنُّوا أَنَّهُم مُّوَاقِعُوهَا" (then they became certain that they would fall therein) where 'dhann' here means certainty, and does this contradict "وَمَا أَظُنُّ السَّاعَةَ قَائِمَةً" (And I do not think the Hour will occur)?

The word "ẓann" (ظن - supposition/thought) appears in the Holy Quran with several meanings: certainty, doubt, accusation, delusion, reckoning, and mistaken belief.

Every instance of "ẓann" in the Quran, when from a believer concerning matters of the unseen in this world, signifies certainty. When from a disbeliever, it signifies doubt. As for "ẓann" regarding the Hereafter, it signifies knowledge and certainty.

The statement of the owner of the garden: (And I do not think the Hour will ever come to pass) is the "ẓann" of a disbeliever in this world, meaning doubt.

There are two rules for differentiating between "ẓann" meaning certainty and "ẓann" meaning doubt: 1. If "ẓann" is found in a praised context, it signifies certainty. If it is found in a blameworthy context, it signifies doubt. 2. Every instance of "ẓann" connected with the lightened "an" (أن) signifies doubt. Every instance of "ẓann" connected with the strengthened "anna" (أنّ) signifies certainty, unless it is connected with the lightened "an" as a verb.