"Why is the believer sometimes the sharpest in behavior?" Imam (as) replied: "Because the honor of the Qur'an is in his heart, and pure faith is in his chest. He is a servant obedient to Allah (swt) and His Messenger (sw), and he is truthful." Imam (as) was asked: "Why is the believer sometimes the most stingy?" Imam (as) replied: "Because he earns his sustenance from lawful means, and seeking lawful sustenance is difficult. Therefore, he dislikes parting with it, knowing how precious it is. But if he is generous, he only spends it where it is appropriate." Imam (as) was asked: "Why is the believer sometimes the most desirous in marriage?" Imam (as) replied: "To protect his chastity from unlawful relations and so that his desires do not sway him in one direction or another. Thus, when he attains what is lawful, he suffices with it and feels no need for anything else." Imam (as) also said: "The strength of the believer is in his heart. Do you not see that he may appear physically weak and thin, yet he stands in prayer at night and fasts during the day?"