Surah 20. Ta-Ha, Ayah 2

I.e., the ethical discipline imposed upon man by the teachings of the Qur’an is not meant to narrow down his feel of life, but, on the contrary, to enhance it by deepening his consciousness of right and wrong.

Allah's revelation may cause some human trouble for two reasons: (1) it checks man's selfishness and narrowness of view, and (2) it annoys the wicked and causes them to jeer and persecute. These are mere incidental things, due to man's own shortcomings. As far as the trouble is concerned, the revelation is meant to give a warning, so that persecutors may be reclaimed, (and of course for men of faith it is comfort and consolation, though that point does not arise in this context).