Part of the mission of the Prophet (pboh) is to purify the body and soul of the followers. This purification is called in the Qur'an tazkiyah.
Abraham had specially prayed to Allah regarding this mission. His prayer is recorded in the Qur'an as follows:
Our Lord, send from among them a messenger of their own, who shall rehearse Your Signs to them and instruct them in Scripture and Wisdom, and purify them. (2:129)
In response to this prayer Allah says:
He it is Who raised from among the illiterate Arabs a Messenger from among themselves, who recites to them His Messages, and purifies them and teaches them the Book and Wisdom. (62:2)
The word tazkiyah entails the removal of undesirable growths and impurities from the personality. It involves the self-imposition of efforts for eradicating those tendencies that are obstacles in the path of moral development. In this way it puts an end to the conflict of good and evil that rages in the human breast.
Tazkiyah is one of the most important ingredients for success in both the worlds physically and spiritually. When practiced it brings spiritual health, morality, love for Allah, love for the Prophet (pboh), engaging in Zikr and becoming a model of Compassion, piety and truthfulness.
This is one of the reasons why Allah says:
Truly, he succeeds who purifies it, and fails who corrupts it (the heart).( 91:9-10)
Tazkiyah e nafs is the purification of the nafs by subduing the evil desires that may be plaguing a person which comes from the whispering of Satan in the breast of men; and because it is from Satan it is evil. In this connection Allah says, the nafs orders one to commit sins.
The result of Tazkiyah is love. The person cultivates love for Allah, for the Prophet (pboh). Allah says:
All who obey Allah and the Messenger are in the Company of those on whom is the Grace of Allah; of the Prophets; the sincere, the witnesses and the righteous. Ah, what a beautiful fellowship. (4:69)
Tazkiyah is a comprehensive program as, in addition to the purification of the body, one also has to focus on the purification of the heart. Allah says:
He is indeed successful who purifies himself, and remembers the name of his Lord and prays. (87:14-15)
Self purification is an individual matter, and every person will benefit based on his effort. Allah says:
And whoever purifies himself does so for the benefit of his own nafs. (35:18)
Prophet Muhammad (pboh) used to pray to Allah as follows:
O Allah, grant my inner soul piety and purify it, for You are the Best Purifier; You are the Guardian and Master.
One of the best ways of developing tazkiyah both physically and spiritually is to keep fast, as in fasting one has to restrain himself from all the negative things, and during fasting in Ramadan he engages himself in extra acts of worship, charity, patience and reading of the Holy Qur'an.
It is now left for the individual to continue practicing tazkiyah in the daily life and also as special acts of worship in order to be a successful person. And Allah will bless him. Allah says:
Those devoted to Allah shall be removed far from it (i.e. the blazing fire), who spend their wealth for the increase in self purification, and have in their minds, no favour from any one for which a reward is expected in return. (92:17-19)
Remember that, it is because the purification of the personality, both physical and spiritual is very important that Allah swore seven times to emphasize the culminating promise that it is tazkiyah that plays a significant role in success. Here is the English translation of Verses 1 through 10 of Surah al Shams (91).
"By the Sun and his (glorious) splendour; By the Moon as she follows him; By the day as it reveals (the Sun's) glory; By the Night as it conceals it; By the Firmament and its (wonderful) structure; By the Earth and its (wide) expanse; By the Nafs (Soul), and the proportion and order given to it and its enlightenment as to its wrong and its right: - truly he succeeds who purifies it, and he fails who corrupts it!"
Let us all strive with our wealth, health, education, etc. to purify ourselves, because it should never be forgotten that Allah says: Whoever purifies himself does so for his own benefit.
May Allah forgive and bless all believers.