That which remains…
That thing that elevates a person is purity, which has different levels, and one of the levels required to reach purity is fasting. Fasting is an act that elevates one to a special level of taqwa (God-consciousness), whose effects can be seen during and after the time of fasting. If a person is vigilant while fasting, the impurities of other parts of the body will go away as well.
Fasting is effective in purifying other qualities within a person. That’s why even permissible acts during a fast are counted as acts of worship. An individual who is fasting is in a state of purification. When he abstains from eating, drinking and having a halal relationship, he becomes pure.
A person who observes a fast that is both correct and is accepted by Allah, he creates a special spiritual relationship with Allah which allows the conditions for the acceptance of supplications to be realized within oneself. Fasting should be in such a way that the whole existence of a person, i.e. all of his physical, imaginal and rational faculties should be in the state of fasting.
If a person, on top of observing the necessary matters of fasting, also pays attention to the ethical aspect of fasting, the positive effects of fasting will gradually begin to penetrate within his soul and his thoughts will also begin to fast, and as a result, this individual will be fasting at various levels. Good deeds cause various changes within a human soul and performing these good acts will become easier for him, among which the best action is the fasting [abstinence] of the heart. The fasting [abstinence] of the heart is to fast [abstain from] with regards to thinking about sins and paying attention to other than God.
Imam Khomeini