The integrals of fasting according to the School (Madh-hab) of Imam Ashafi^iyy are two:
1. To make the intention each night to fast the following day of Ramadan.
2. To abstain, during the time from the dawn until sunset, from inserting any substance into the head or the body cavity through an open inlet, excluding one's pure, tahir saliva while still inside the mouth and to abstain from sexual intercourse, masturbalion, inducing vomit, and apostasy.
Making the intention at night to fast the following day of Ramadan means to have the intention in one's heart to fast during the night preceding the fasting day, i.e., after the sunset and before the dawn (fajr) of the following day. Sometime during that time, the person must make the intention to fast the following day. This must be done each night for the following day of fasting. As related by at-Tirmidhiyy, an-Nasa'iyy, and others, the Prophet صلى الله عليه وسلّم said:
which means: <<There is no fasting for the one who does not establish the intention for fasting the previous night.>>
The intention is in the heart, and does not have to be uttered with the tongue. The one who sleeps at night without having had the intention to fast and wakes up after dawn misses the time of the intention. Although fasting is not valid for him that day, he is obligated to abstain from whatever a fasting person must abstain from that day. In addition, he must later make up that day. This matter however differs according to other schools of thought (madh-habs).
If the menstrual or postpartum bleeding of a woman stops at night, then she must intend to fast the following day. The purificatory bath (ghusl) is not required for her to start fasting, but rather to start praying. The intention for any obligatory fasting of Ramadan must take place the night before the fast. However, the intention time for an optional fasting is extended until Dhuhr time, as long as one does not commit any of the invalidators of fasting since the dawn appeared.
The fasting person must abstain from taking into his body cavity any substance from an open inlet, whether this substance is food, drink, or otherwise. A person's fast is invalidated if he intentionally inserts such a substance during the fasting day, while remembering he is fasting and knowing that it is unlawful to do so. This person must make up the fast day(s) he invalidated without a valid islamic excuse. The open inlets of the body are the mouth, nose, anus, vagina, and others. 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.
Swallowing one's own pure saliva, while still inside the mouth, does not invalidate the fast. However, the fast would be invalidated if some saliva dangled outside the mouth, and separated from the tongue, even to the lips, then was taken back in and swallowed. In addition, if the saliva in the mouth is mixed with something else, whether pure or not, then swallowed, this invalidates the fast.
One's fast is not invalidated by what is too hard to protect oneself from swallowing. This includes the dust of the street, the dust of the flour, and the like. Although smoking a cigarette breaks the fast of the smoker himself, it does not break the fast of a passive smoker (the person next to him who breathes in some of the smoke). Also, it does not break the fast of one who breathes in the odor of incense or other fragrances, however if one deliberately breathes in the particles which come out of a spray bottle (whether perfume or the like), while remembering that one is fasting, then one's fast is terminated.
Another condition for the validity of fasting is for one to abstain from sexual intercourse during the day of fasting. If the person does not know that he must abstain from sexual intercourse during the fasting day, or he forgets that he is fasting and performs this act, then this does not invalidate his fast. However, the man or woman who performs sexual intercourse during the day of fasting while knowing it is unlawful to do so and remembering that he/she is fasting, does invalidate his/her fast.
The expiation, which is due on the man only, for invalidating his fasting by sexual intercourse is in the following order:
1. To free a Muslim slave,
2. If unable, then to fast two consecutive lunar months, in addition to making up the day which was invalidated by his sexual intercourse;
3. If unable, then to feed each one of sixty (60) poor Muslims a pair of average-sized hands cupped together (i.e, one mudd) filled with the most common staple food of the area.
Masturbation by one's own hand or the hand of one's spouse, or making the maniyy (sexual spermatic fluid from the man or the woman) discharge by kissing or other physical contact invalidates one's fasting. If, however, one experienced a wet dream or maniyy exited from one because of certain thoughts, one's fast is not invalidated.
One's fasting is invalidated by forcing oneself to vomit, either by inserting the finger into the mouth or otherwise. In the case when one forces one to vomit, whether or not one swallows some of one's vomit, one's fast is invalidated and one has to make up that invalidated day. However, the one who vomited involuntarily (without purposely forcing oneself to do so) does not break one's fast as long as one does not swallow any of the vomit or saliva mixed with the najas-filthy vomit.
There are different sayings regarding the phlegm or congestion that drips from the nasal passage 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' ح is, and the person swallowed it, this would invalidate his fasting. However, according to Imam Abu Hanifah, even if the phlegm reaches to the tongue and the person swallows it, his fasting is not invalidated, as long as he does not swallow it after it separates from his mouth.
Finally, the Muslim must abstain at all times from committing apostasy, i.e., committing any type of blasphemy which takes him out of Islam such as swearing at Allah سبحانه وتعالى or one of the Prophets of Allah, throwing the Qur'an in the trash, making mockery of the religion, objecting to the will of Allah تعالى and so on.
Apostasy invalidates Fasting, even if one returns to Islam immediately afterwards by saying the Shahadah (two testifications of Faith). After returning to Islam, One must abstain from eating and other invalidators of Fasting during the whole day. Moreover, One must make up the invalidated day(s) of Fasting after Ramadan.
And Allah The Exalted knows best.