﴿ وَإِن مَّا نُرِيَنَّكَ بَعْضَ ٱلَّذِى نَعِدُهُمْ أَوْ نَتَوَفَّيَنَّكَ فَإِنَّمَا عَلَيْكَ ٱلْبَلَٰغُ وَعَلَيْنَا ٱلْحِسَابُ ﴾

“BUT WHETHER We let thee see [in thy lifetime, O Prophet, the fulfilment of] some of what We have promised them, or whether We cause thee to die [before its fulfilment] - thy duty is no more than to deliver the message; and the reckoning is Ours.”

And whether read as immā the nūn of the conditional particle in ‘whether’ has been assimiliated with the extra mā We show you a part of that which We promise them of chastisement during your lifetime the response of the conditional statement has been omitted in other words understand it as being fa-dhāk ‘then so shall it be’; or We take you to Us before chastising them; it is for you only to convey the Message your duty is only to deliver the Message and it is for Us to do the reckoning when they finally come to Us whereupon We shall requite them.