The greatest of all preachers is the Book of Allah, for He says:
“O mankind, there has come to you an admonition from your Lord, a healing for what is in the breasts, and guidance and mercy for the believers” (10:57).
Accordingly, nothing offers more powerful counsel than the Qur’an. It brings together encouragement and warning; it speaks of Paradise and Hell, of the righteous and the wicked. In short, it is the supreme source of admonition.
Yet it only produces this effect in the one “who possesses a heart or listens attentively while he is present” (50:37). As for those whose hearts have hardened—may Allah protect us—He says: “Whenever a surah is revealed, some of them ask, ‘Which of you has this increased in faith?’ As for those who believe, it increases them in faith and they rejoice” (9:124). Thus, every time a believer recites from the Book of Allah, his faith grows stronger and he is gladdened by the light that Allah has placed in his heart through this magnificent Book. “But those in whose hearts is a disease—it only adds filth to their filth, and they die while they are disbelievers” (9:125). We seek refuge with Allah from such a fate.
Therefore, one should exhort people with the Qur’an, the Sunnah, the words of the leading scholars, and every discourse that softens hearts and turns them toward Allah. The author, may Allah have mercy on him, next points out that moderation is required in delivering admonition,