...The Quran contains Islamic Monotheism; Allah’s promises, warnings and Commandments; stories of previous nations; and codes of the best conduct and behavior. These various subjects in the Quran have different effects on the heart. Some Surahs (chapters) of the Quran are more frightening than others.
The Messenger of Allah said, what translated means, "Hud (chapter 11) and its sisters (chapters 56, 77, 78 and 81) have brought me white hairs before their due time." [As-Silsilah As-Sahihah].
and he was clearly heard by those who were standing behind him. Furthermore, Uthman ibn `Affan said, "If our hearts were pure, they will never have enough from reciting Allah’s Speech (the Quran)."
"Then every person shall be paid what he earned, and they shall not be dealt with unjustly." [Surah Al Baqarah 2:281].
and then fell in Sujud. Then, he said to himself, "Here you are, you do the Sujud, so where is the crying?"
...Ibn Al-Qayyim said with regards to what one should do to cure his weak Iman using the Quran, "First you should remove your heart from the life of this world and settle it in the Last Life. Then, pay your full attention to pursuing the meanings of the Quran, and try to comprehend and understand them and what they were sent down to accomplish. Then, offer these meanings to the sickness that your heart feels, and when they touch the disease, they will cure the heart, Allah willing."