Surah Ha-Mim as-Sajdah, Footnote 38

That is, this remedy is indeed highly effective, but putting it into practice is no light matter. It requires great courage of heart. It demands strong resolve, great fortitude, immense capacity to endure, and firm mastery over one’s own self. A person can, momentarily, display great goodness in the face of some particular evil—that is nothing extraordinary. But where someone must struggle for years on end, for the sake of truth, against wicked devotees of falsehood who hesitate at no bound of morality, and who, moreover, are intoxicated with the arrogance of power and authority—there, to keep meeting evil with goodness, and goodness of the highest order at that, without ever once letting go of the reins of self-control, is not within the capacity of any ordinary person. This can only be achieved by someone who has made a firm, level-headed resolve to work for the supremacy of truth, who has brought his own self fully under the command of reason and awareness, and in whom goodness and righteousness have taken root so deeply that no mischief or malice of his opponents can ever succeed in dragging him down from that lofty station.