﴿ فَكَيْفَ كَانَ عَذَابِى وَنُذُرِ ﴾

“And how severe is the suffering which I inflict when My warnings are disregarded!”

How dreadful then were My chastisement and My warnings? this is an interrogative meant as an affirmative; kayfa ‘how’ is the predicate of kāna ‘was’ and it is here being used to inquire about a ‘state’; the intention is to prompt those who are being addressed to affirm the fact that God’s chastisement of those who denied Noah was fully deserved.