That thing which elevates a person is purity

That thing which elevates a person is purity, which has different levels, and one of the levels required to reach purity is fasting.
Fasting is an act which 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 an effective act in purifying other qualities within a person. That is why even permissible (mubah) 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 accepted by Allah creates a special spiritual relationship with Allah which enables 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, all of his physical, imaginal and rational faculties should be in the state of fasting.
If a person, on top of observing the necessary aspect of fasting, also pays attention to the akhlaqi (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 induvial will be have higher levels of fasting.
Good deeds cause changes within a human soul and performing these good acts will become easier for him. One of the most important actions is the fasting of the heart. The fasting of the heart is to fast [abstain] from thinking about sinning and from paying attention to other than God.

Imam Khomeini