Translation of the verse 40 from Surah Ar-Ra‘d : Number of verses 43 - - page 254 - Part 13.
Whether We show you (O Muhammad SAW) part of what We have promised them or cause you to die, your duty is only to convey (the Message) and on Us is the reckoning.
And whether We show you part of what We promise them or take you in death, upon you is only the [duty of] notification, and upon Us is the account.
(13:40) And O Prophet! Rest assured that We will carry out the threat We are holding out to them whether a part of it should happen during your lifetime or We should cause you to die before its fulfilment. Anyhow your duty is only to convey the Message and it is for Us to do the reckoning. *59
*59) This is to console the Holy Prophet, as if to say, "O Prophet, you need not concern yourself as to the end of these disbelievers who have rejected the Truth. You should go on performing with peace of mind the Mission that has been entrusted to you and leave it to Us to give them suitable punishment. " Though this has been addressed to the Holy Prophet, it is obvious that it is really meant to warn the opponents of the Truth, who were demanding definitely from the Holy Prophet by way of a challenge to bring about the scourge about which threats were being held out to them.