'Indeed, it is a part of a man's growth in knowledge to improve his Iman,
make up for any decrease, know whether his Iman increases or diminishes, and
know when and where Satan's temptations may come."' Also, Ismail Ibn
Ayyaash narrated, on the authority of Safwan Ibn Amr, on the authority of Abd
Allah Ibn Rabi’ah al-Hadrami, on the authority of Abu-Hurayrah, who said:
"Iman increases and diminishes." Ahmad Ibn Hanbal related, on the
authority of Yazid Ibn Harn, on the authority of Muhammad Ibn Talhah, on the
authority of Zubayd, on the authority of Dharr said: Umar Ibn al-Khattab used to
say to his companions:
'Let us increase our Iman [they hold Allah in remembrance]."' In the
book of Gharib ul-Hadith, Abu Ubayd related the hadith of Ali which says:
"Iman resembles a white spot on the heart; whenever Iman increases, the
white spot increases as well." It was related on the authority of Uthman
Ibn Abd Allah and Amr Ibn Hind al-Jumali that al-Asmai said: "A lamzah,
spot, is like a speck or something similar."
Allmad Ibn Hanbal narrated, on the authority of Waki on the
authority of Sharik, on the authority of Hilal and on the authority of Abd Allah
Ibn Akim, who said:
"I heard Ibn Masud saying in his prayer: 'Oh, Allah, increase our Iman,
our conviction, and our knowledge [about religion]."' Similarly, Sufyan
al-Thawri narrated, on the authority of Jami Ibn Shaddad and al-Aswad Ibn Hilal,
who said:
Mu’adh Ibn Jabal used to tell a man: 'Let us sit down to hold Allah in
remembrance [in order to increase our Iman]."' Also, Abu al-Yaman narrated, on the authority of Safwan and Shurayh Ibn Ubayd who
said that Abd Allah Ibn Rawahah used to take the hand of one of his companions
and say: "Let us get up in order to increase our Iman for an hour in a
posture that holds Allah in remembrance." This increase in Iman was
affirmed by the Companions of the Prophet (sallallaahu alayhi wasallam) after his death and after the
revelation of the whole Quran.
It was affirmed that Ammar Ibn Yasir said: "Three characteristics lead
anyone who possesses them to have true Iman: to be just to oneself, to spend in
spite of poverty, and to offer greetings to everybody [to those you know and to
those you do not know]." Al-Bukhari recorded this in his Sahih. Also,
Jundub Ibn Abd Allah, Ibn Umar, and others said: "We learned Iman, then we
learned the Quran, and in turn increased our Iman. Indeed, there are many other
sayings narrated on the authority of the Companions and their Successors that
support the fact that Iman either increases or diminishes.
[Malik Ibn Dinar said that belief in one's heart appears as weak and as frail
as a small herb plant. If one cares for it, watering it with useful
knowledge and good works, removing the thick underbrush that grows up around it
and anything else that might weaken or thwart its growth, then soon it will
thrive and increase. First it will grow roots, then branches, then fruits, until
at last it rivals the mountains in size, casting shade that extends out to
infinity. If, however, one shows no concern for it and neglects it, goats will
come and pull it out by the roots, some little boy will carry it off, or the
thicket will grow up around it, weakening or perhaps destroying it or depriving
it of its moisture. And as this plant is, so also is belief.
Khaythamah Ibn Abd al-Rahman said that belief grows fat in times of
fertility, and wastes away in times of drought. Its times of fertility are
provided by good works, while its times of drought are brought on by sins and
acts of disobedience.
One of the pious ancestors was asked: "Is it possible for belief to
increase and decrease?" "Yes," he replied, "it can grow
until it towers like a mountain, or shrink until it is no larger than a particle
of dust."