The Prophet said, “Religion was founded on cleanliness.” And again, “Purification is the key to prayer.” God said, ” Therein are men who aspire to purity, and God loveth the purified.” The Prophet also said, “Purification is one half of belief.4 God also said, “God desireth not to lay a burden upon you, but He desireth to purify you.” Through these externals, those who possess insight awoke to the fact that the most important thing is the purification of the heart, because, it is very unlikely that the words of the Prophet, “Purification is one half of belief’ meant that men should polish and clean the body with a generous use of water and to neglect the heart and leave it stuffed with impurities and filth.
Source and Recommended Reading:
'The Mysteries of Purification: Book 3 of the Revival of the Religious Sciences'
By Abu Hamid Al-Ghazali (Author)
In the The Mysteries of Purification (Kita b asra r al-t aha ra), the third of the forty books of the Revival of the Religious Sciences (Ih ya ulu m al di n), Abu H a mid al-Ghaza li explains the fundamentals of the purification that is necessary in order to perform the five daily prayers. The book begins with an introduction to the general topic of purity. Al-Ghaza li explains the h adi th Purification is half of faith, and reminds readers that, for the earliest Muslims, inner purification was much more important than outer purification.