Hudhayfah said in one of his sound traditions: "One might say of a certain man: 'How long-suffering he is!' 'How witty he is!' or, 'How wise and judicious he is!' even though he does not have belief in his heart the size of a grain of mustard seed." In his other sound traditions we read that "the charms and attractions [of the world] are presented to people's hearts as a mat is spread out [over the floor], one reed at a time. Any heart that partakes of them is stained with a black spot, while any heart that spurns them will take on a white spot until there comes to be two types of heart: one as white as a stone, which may never be harmed by temptation as long as the heavens and earth remain, and the other as black as an overcast sky, like an overturned earthen vessel that neither recognizes a good deed nor shuns an evil one except that which follows its own desire." As for the tradition concerning the seventy thousand who enter Paradise without being called to account for [the sufficiency of] their deeds, it provides the most convincing evidence that belief may indeed increase or diminish, since the seventy thousand are described as having powerful, growing belief [that may be seen] through those qualities and attributes that make their belief manifest, and through their dependence on Allah in all of their affairs.

Abu Naim related, based on the account of al-Lay Ibn Sad, on the authority of Zayd Ibn Allah al-Yazni, on the authority of Abu Rafi, who said that a man related to him asked the Messenger of Allah (sallallaahu alayhi wasallam) about belief. In response he said: "Do you want me to tell you what pure, unadulterated belief is?" "Yes," the man replied. "To have such belief means that if you offend or wrong anyone, be it your male or female slave or anyone else, you feel grief and regret; or if you give charity and do good, you feel joy and satisfaction." A similar tradition is related by others on the authority of Yazid, on the authority of those who heard the Prophet (sallallaahu alayhi wasallam), when someone asked him about whether belief in one's heart may increase or diminish, in reply to which the Prophet gave the response mentioned above. In addition, al-Bazzar said that it was related to us by Muhammad Ibn al Hassan al-Basri, on the authority of Hani' Ibn al-Mutawakkil, on the authority of Abd Allah Ibn Sulayman, on the authority of lshaq, on the authority of Anas from the Prophet, who said: "There are three things that, if found within a person, cause him to merit reward and bring his belief to perfection: a temperament that enables him to live [peaceably] among people, piety that shields him from danger of disobedience to Allah, and a patient, forbearing spirit by which to ward off the ignorance of the ignorant. And there are four things that cause misery to those in whom they are found: a rigid outlook, hardness of the heart, excessive ambition, and greed for the things of this world." The first group of attributes indicates the increase and strength of one's belief, while those in the second group are evidence of its weakness and diminution.

Abu Yala al-Mawsili said that it was related to him by Abd Allah al-Qawariti and Yahya Ibn Said, on the authority of Yazid Ibn and Yahya Ibn Said, who said that it was related to them by Awf that he heard from (qah Ibn Abd Allah al-Mazni that Yazid said in his hadith at the mosque in Basrah: "I was told by a man [whose name Awf had forgotten] that he was in Madinah in a mosque with Umar Ibn al-Khattab and Umar said to one of those who were seated with him: 'What have you heard the Messenger of Allah (sallallaahu alayhi wasallam) say about Islam?' The man replied: 'I heard him say that Islam began as a single tree trunk; then it was doubled, and then quadrupled. After this it grew to six times and finally flourished.' Then Umar said to the man: 'And what can happen after flourishing but that it should diminish?"' This is how it was related by Abu Yala in Musnad Umar; although in the Musnad of this obscure Companion of the Prophet its mention is more appropriate.