﴿ قُلْ هُوَ ٱلرَّحْمَٰنُ ءَامَنَّا بِهِۦ وَعَلَيْهِ تَوَكَّلْنَا ۖ فَسَتَعْلَمُونَ مَنْ هُوَ فِى ضَلَٰلٍۢ مُّبِينٍۢ ﴾

“Say: "He is the Most Gracious: we have attained to faith in Him, and in Him have we placed our trust; and in time you will come to know which of us was lost in manifest error."”

When the addressee is not convinced by reasoning, the preacher repeats his utterances of firm faith and thus stirs his inner self into awakening. Even if there is the slightest sensitivity in a man, these last utterances are enough to make him feel the urge to reform himself. But one whose conscience has been completely blunted, can never be awakened by any device.