ثُمَّ لَتَرَوُنَّهَا عَيْنَ الْيَقِينِ
Then you will surely see it with direct certainty. (التكاثر: 7)
In la-tarawunnahā, the object pronoun -hā refers back to al-jaḥīm. ʿAyna al-yaqīn draws attention to certainty through direct sight. Its appearance after ʿilma al-yaqīn gives a discernible progression of presentation: certain knowledge is followed by a scene of seeing.
Thumma marks this advance. The repeated reference to seeing should not be dismissed as surplus, since the pronoun, the new qualifier, and the surrounding discourse add meaningful detail and force.