بَلِ ٱلَّذِينَ كَفَرُوا۟ فِى تَكْذِيبٍۢ
Sentence structure
بَلِ resumes with contrast. ٱلَّذِينَ is the nominative topic and كَفَرُوا۟ its relative clause; فِى تَكْذِيبٍ is the predicate.
Ayah summary
Instead of taking warning from earlier events, the deniers persist in rejecting the truth.
بَلِ — Nay
Grammar: A non-governing contrastive/resumptive particle; its final kasra avoids two consonants meeting.
ٱلَّذِينَ — Those who
Grammar: A masculine-plural relative pronoun functioning as the nominative topic; its relative clause follows.
كَفَرُوا۟ — disbelieve
Grammar: A third-person masculine-plural perfect forming the relative clause. Attached و is the subject and the final alif is orthographic.
فِى — (are) in
Grammar: A preposition; the phrase فِى تَكْذِيبٍۢ functions as the predicate of ٱلَّذِينَ.
تَكْذِيبٍۢ — denial
Grammar: An indefinite Form II verbal noun in the genitive after فِى.