Tafsir of Al-Ahzab 33:66

(The Day their faces will be turned in the Fire) is an adverbial phrase for "lacking" [their find/attainment], and it is said [it relates] to "abiding therein," and it is said [it relates] to "We shall turn," and it is said [it relates to] an omitted object—meaning: the day their faces will be turned within it from one side to another, like meat being roasted on a fire or cooking in a pot, which the boiling water turns from side to side; or, the day their faces change from one state to another, as ugly appearances descend upon them due to the intensity of the terrors; or, the day they are cast into the Fire inverted and upside down. The specification of the faces is mentioned because they are the noblest of members, thus it contains an increase in the horror of the matter and an intimidation of the calamity. It is permissible for it to be an expression for the entire body.

Al-Hasan, ‘Isa, and Abu Ja‘far al-Rawasi recited tuqallabu with a fatha on the ta’; the origin is tataqallabu, and one of the two ta’s was elided. Ibn Abi ‘Abla recited it with both [as tataqallabu] according to the original form. Ibn Khalawayh narrated from Abu Haywa that he recited nuqallibu wujuhahum, attributing the verb to the pronoun of majesty [God] and placing wujuhahum in the accusative as the object.

‘Isa al-Kufi recited tuqallabu wujuhahum, attributing the verb to the pronoun of the Fire [the Sa‘ir] by extension, and placing wujuh in the accusative.

(They will say) is an initiation based on a question arising from the narration of their horrific state, as if it were said: "What will they do at that time?" So it was said: They will say, expressing regret for what they have missed: (Would that we had obeyed Allah and obeyed the Messenger), so that we would not be afflicted with this torment. [This] is a state for the pronoun of "their faces" or from the faces themselves.

It is permitted that it [the verb "they say"] be the one that places "the Day" in the accusative.