Surah 22. Al-Hajj, Ayah 49

It is the Messenger's duty to convey the warning in the clearest terms to the wicked. It is no part of his duty to coerce them or judge them, or bring on the Punishment for them. That only rests with Allah. But the warning itself is full of Mercy: for it gives the highest hope to the repentant sinner who turns and comes to Allah.