Faith increases and decreases — Sahih al-Bukhari | Quran & Hadees
Faith increases and decreases
And the Statements of Allah جل جلاله, "We increased them in guidance." (V.18:13) "And the believers may increase in faith." (V.74:31) — And Allah تعالى said, "This day I have perfected your religion for you," (V.5:3)
(The last Statement indicates that) if somebody leaves a part of (from) the perfection of the religion then his religion is incomplete.
Narrated Anas:
The Prophet (ﷺ) said, "Whoever said "None has the right to be worshipped
but Allah and has in his heart good (faith) equal to the weight of a
barley grain will be taken out of Hell. And whoever said: "…
Narrated 'Umar bin Al-Khattab:
Once a Jew said to me, "O the chief of believers! There is a verse in
your Holy Book Which is read by all of you (Muslims), and had it been
revealed to us, we would have taken that day…