Tafsir of Ghafir 40:70

الذين كذبوا بالكتاب وبما أرسلنا به رسلنا

Those who deny the Book, and that with which We sent Our Messengers, means, guidance and clear proof.

فسوف يعلمون

they will come to know. This is a stern warning and clear threat from the Lord to these people. This is like the Ayah:

ويل يوميذ للمكذبين

Woe that Day to the deniers! (77:15)