However, it should be understood that most of those who have gone astray in this matter, or have been unable to discern the truth concerning it, have done so because they neglected to follow what the Messenger brought and abandoned the reflection and reasoning that lead to knowledge of the truth. When they turned away from the Book of Allah, they went astray, as Allah Most High says:

“O children of Adam, if messengers from among you come to you, recounting My verses to you, then whoever fears Allah and reforms—no fear will be upon them, nor will they grieve.”
[al-A‘rāf: 35]

And His words:

“He said, ‘Go down from it, both of you together, as enemies to one another. Then if guidance comes to you from Me, whoever follows My guidance will neither go astray nor suffer. * But whoever turns away from My remembrance will have a life of hardship, and We will raise him blind on the Day of Resurrection.’”
[Tā Hā: 123–124]

Ibn ‘Abbās said: Allah has guaranteed that whoever reads the Quran and acts upon what it contains will neither go astray in this world nor suffer in the Hereafter. He then recited this verse.

Likewise, in the hadith recorded by al-Tirmidhī and others:

“‘Alī, may Allah be pleased with him, said: The Messenger of Allah, peace be upon him, said, ‘There will be trials.’

I asked, ‘What is the way out of them, O Messenger of Allah?’

He said, ‘The Book of Allah,