Tafsir of An-Naba' 78:4-5

{Nay, they shall come to know.}

It is a rebuke to those who ask questions in mockery.

{Then, nay, they shall come to know.}

It is a threat to them that they will eventually realize that what they are questioning and mocking is the truth, for it is an occurrence in which there is no doubt.

The repetition of the rebuke alongside the threat serves to emphasize it. The meaning of {then} is to signal that the second threat is more profound and severe than the first.

{Have We not made the earth a resting place? And the mountains as stakes? And We created you in pairs? And We made your sleep a repose? And We made the night a covering? And We made the day for livelihood? And We built above you seven strong ones? And We made a burning lamp? And We sent down from the rain-clouds pouring water? That We may bring forth thereby grain and vegetation? And gardens of dense foliage?}