Surah 4. An-Nisaa', Ayah 80

The Messenger was sent to preach, guide, instruct, and show the Way,-not to drive people to good. That is not Allah's Plan, which trains the human Will. The Messenger's duty is therefore to convey the Message of Allah, in all the ways of persuasion that are open to him. If men perversely disobey that Message, they are not disobeying him but they are disobeying Allah. In the same way those who obey the Message are obeying Allah. They are not obliging the Messenger: they are merely doing their duty.