Then, no! They are going to know. (78:5)

Almuntakhab Fi Tafsir Alquran Alkarim

No, but indeed they shall soon come to know. Then Allah reminds them by drawing their attention to His omnipotence; He says

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(78:5) again, no indeed; soon will they come to know.

Then, no! They are going to know. meaning

*3) That is, the time is not far off when the same thing about which they are expressing all sorts of meaningless doubts and misgivings, will appear before them as a reality. Then they will realize that what the Messenger had foretold was absolutely true and what they were saying on the basis of conjecture and speculation had no truth in it.
 

Then, no! They are going to know. meaning in Urdu

ہاں، ہرگز نہیں، عنقریب اِنہیں معلوم ہو جائے گا