ثُمَّ يُقَالُ هَـٰذَا ٱلَّذِى كُنتُم بِهِۦ تُكَذِّبُونَ
Sentence structure
Passive يُقَالُ introduces reported speech, and the complete reported nominal clause occupies its deputy-subject position. Within that clause هَـٰذَا is the topic; in one grammatical reading ٱلَّذِى is its predicate and كُنتُم بِهِۦ تُكَذِّبُونَ the relative clause.
Ayah summary
They will be told that this is the very punishment they used to deny.
ثُمَّ — Then
Grammar: a conjunction.
يُقَالُ — it will be said
Grammar: A third-person masculine-singular passive imperfect; the reported nominal clause fills its deputy-subject position.
هَـٰذَا — This
Grammar: A masculine-singular demonstrative functioning internally as the topic; the whole reported clause occupies the deputy-subject position of يُقَالُ.
ٱلَّذِى — (is) what
Grammar: A masculine-singular relative pronoun, used as the predicate of هَـٰذَا in this grammatical reading; its relative clause follows.
كُنتُم — you used to
Grammar: A deficient second-person masculine-plural perfect; attached تُم is its nominative noun.
بِهِۦ — [of it]
Grammar: بِ is a preposition and attached هِۦ its genitive pronoun; the phrase is linked to تُكَذِّبُونَ.
تُكَذِّبُونَ — deny
Grammar: A Form II second-person masculine-plural imperfect forming the predicate of كُنتُم. Attached و is the subject and final ن marks the indicative.