1. Each night to make the intention to fast the following day
2. To abstain from sexual intercourse, masturbation, and inserting anything with a volume into the head or the body cavity through an open inlet, excluding one’s pure, tahir saliva while still inside the mouth during the time from the dawn until the sunset.

Making the intention at night to fast the following day means to have the intention to fast in one’s heart during the night preceding the fasting day, i.e., after the sunset and before the dawn of the following day. Sometime during that time the person must make the intention to fast the following day, and this must be done each night for the following day.

As related by at-Tirmidhiyy, an-Nasa’iyy, and others, the Prophet said what means: <<There is no fasting for the one who does not establish the intention for fasting the night before.>>

The intention is in the heart, and does not have to be uttered with the tongue. The one who slept at night without having had the intention to fast and woke up after the dawn is obligated to abstain from whatever a fasting person would abstain and then fast a make up for that day. If the menstrual or postpartum bleeding of a woman stopped at night, then she must intend to fast the following day. The purificatory bath is not required to start fasting, but   

The intention for any obligatory fasting during Ramadan, must take place the night before the fast.  

However, for the one who is fasting an optional fast, it is not a condition that he must intend to do so the preceding night. It is valid for him to have the intention to fast that same day during the morning, before the sun moves from the center of the sky towards the west, as long as he had not committed any of the invalidators of fasting since the dawn appeared.

The fasting person must abstain from taking into his body cavity any material that has a tangible volume from an open inlet, whether this material was food or drink or other than that. If a person intentionally takes into his body cavity any material that has a tangible volume during the fasting day, while remembering he is fasting, and knowing that it is unlawful to do so, and not because another threatened to kill him (or the like) if he did not break his fast, then this invalidates his fast, and he has to make it up.

The open outlets of the body are like the mouth, nose, anus, vagina, and other.

Materials which are absorbed by the pores of the skin do not invalidate the fast because the pores of the skin are not considered to be an open inlet to the body cavity. For example, rubbing oil into the skin does not invalidate the fast.

One’s own pure saliva, while still inside the mouth, if swallowed, does not invalidate the fast. If some saliva was spit outside the mouth, and separated from the tongue, even to the lips, then was taken back in and swallowed, it would invalidate the fast. However, if the saliva is mixed with something else, even something pure, then swallowed, it invalidates the fast.

In what is too hard to protect oneself from swallowing, like the dust of the street or the dust of the flour and the like, one’s fast is not broken. Although smoking a cigarette breaks the fast of the smoker himself, it does not break the fast of the person next to him who breathes in some of that smoke. Neither does it break the fast for one to breathe in what is other than a physical entity, like the odor of incense or other fragrances.

Also among the conditions for the validity of fasting is for one to abstain from sexual intercourse during the day of fasting. If the person did not know that one must abstain from sexual intercourse during the fasting day, or he forgot that he was fasting and he performed this act, then it does not invalidate his fast. However the man or woman who performs sexual intercourse during the day of fasting while knowing this is unlawful and remembering he is fasting, would invalidate his/her fast by that. The expiation due for invalidating one’s fasting by sexual intercourse is in the following order:

1. To set a Muslim slave free;
2. If he was unable, then to fast two consecutive months, other than making up the day which was invalidated by his sexual intercourse;
3. If unable, then to feed each one of 60 poor people two cupped, average-sized handfuls of the most common staple food of the country.

Masturbation or making the semen come out of one by using the hand or the like invalidates one’s fasting, whether one used his own hand, or the hand of his wife, or because of a kiss, or because of other physical contact. If, however, one experienced a wet dream or semen exited from him because of certain thoughts, one’s fast is not invalidated.

For one to force himself to vomit, either by inserting his finger or other than that into his mouth invalidates the fasting. In the case when the person forces himself to vomit, whether or not he swallows some of his vomit, his fast is invalidated and he has to make it up. However, the one who vomited not because he purposely forced himself to do so does not break his fast as long as he does not swallow any of the vomit or saliva mixed with the najas-filth.

There are different sayings regarding the phlegm or congestion that drips from the head  into the throat.

According to Imam ash-Shafi^iyy if the phlegm reached to the part of the throat above where the exit of the letter ha’ is, and the person swallowed it, this would invalidate his fasting.

However, according to Imam Abu Hanifah, even if the phlegm reached to the tongue and the person swallowed it, his fasting is not invalidated, as long as he does not swallow it after separating from his mouth.