There are many conditions for the fast to be obligatory and for it to be carried out correctly:
585. It is a condition that the person fasting is a Muslim, so fasting by a non-Muslim is not valid.
586. It is not obligatory for someone who has not reached the Islamic legal age (buloogh) to fast, but if he/she does fast, it is valid and they will be rewarded for it.
587. Fasting is not obligatory for the insane, nor is it valid if an insane person does.
4- Purity from the haydh and nifas:
588. It is a condition for a woman’s fast to be pure from the menses and nifas from dawn to sunset, so fasting by a woman during her period or nifas is not obligatory, nor is it valid if she does; this is even if the menses or nifas took place at one moment of time within the period between dawn and sunset, making the fasting of that day void.
589. It is conditional for a valid fast not to harm the fasting person; such harm may take place if the fast causes illness, intensifies an existing illness, delays its cure or intensifies the pain, whether one is certain of this or thinks that it is probable in a way that one fears harm – in all that, fasting is not obligatory, and only the opinion of a competent doctor is sufficient, unless the person is satisfied that the opposite is the case.
590. If a person fasts while he fears harm or believes he might be harmed, then if the harm does take place, his fast becomes void; if no harm takes place and the expected harm was one that anyone must protect oneself from, the fasting is also void, otherwise the fast is valid.
591. If he fasts believing that no harm will take place, then he finds out that the fast is harmful, in this case his fast remains valid.
6- No travelling:
592. It is conditional for a valid fast not to be undertaking the type of journey that makes qasr in prayers (shortened prayer) obligatory, so the fasting of a traveller is not valid except if he has vowed to fast while travelling, in which case the fast is valid as a vow not as part of Ramadan, even if he did make the vow of fasting during it. Also, fasting is valid by a pilgrim, performing Hajj-ut-Tamattu‘ (performing pilgrimage with umrah; for details of pilgrimage, see another reference), who is unable to slaughter the animal (hadi), and by a pilgrim who is unable to offer atonement when leaving (kaffarat al-Ifadhah) ‘Arafat.
593. The ruling that a fast by a traveller is void only applies if he knew the ruling – that a traveller’s fast is not acceptable – so if a traveller fasts out of ignorance of the ruling, or some of its details, his fast remains valid; but if he comes to know this during the day, his fast becomes void specifically on the day the knowledge was acquired, but not for the days before that. That said, fasting is not acceptable for a traveller who has forgotten the ruling or that he was regarded by the Shariah as a traveller.
594. If the fasting traveller wants to fast, there are two situations:
First: That he travels after noon (dhuhr); in this case he is absolutely not allowed to break fast.
Second:That he travels before noon; in this case fasting on that day is not valid. In such cases, it is not allowed for the traveller to take anything which breaks the fast (mufattirat) until he passes the Hadd at- Tarakhus, which is the place where he will only appear as a ghost without defined features for the onlookers from the town’s last house (see Chapter 4: Prayer of the traveller.)
But in the second case, if the traveller enters one of his homelands, or a place in which he intends to reside for ten days or more, in this case there are several situations:
a- That he enters it after zawal (the moment the sun starts to move towards sunset, which is the start of the time of the noon prayer); here he must break the fast, and fasting is not acceptable. It is recommended that he abstains from things which break fasting however.
b- That he enters it after zawal, in which case there are two situations:
1- He has taken, during his journey, things which break the fast; in this case he must break the fast, although it is recommended that he abstains from such things.
2- He has not taken, during his journey, anything which breaks the fast; in this case he must set the intention of fasting and fast the rest of the day, making that an acceptable fasting day.
595.It is allowed to travel in the month of Ramadan, even if without necessity, and even if to escape from fasting; it is makruh (recommended to abstain from it) however.
596.Fasting is not valid from someone who is unconscious if he lost his consciousness before dawn and before the intention, but it is valid - rather it is obligatory - to continue fasting if this took place after the intention, whether it took place before dawn or after it. Included in unconsciousness is what takes place due to general anaesthetics given in surgical operations; however it is different to the former as far as the obligation to perform qadha’ is concerned.
8- He must not have an excuse not to fast:
597.The Shariah allows certain people to break their fast:
1- A person who suffers from weakness and lethargy, so if he fasts, fasting will cause difficulties for him and intensify his weakness to the extent that he becomes unable to stand up, walk or carry out his usual daily activities.
2- Men and women who have reached seventy years, which is the age of elderly people that is accompanied by a weakness which makes fasting completely impossible, or very difficult for them.
3- People who practise very hard jobs, so fasting would weaken them or cause intense thirst that is extremely hard to withstand, and provided that they are unable to find another more comfortable job or savings (money) or a loan that can help them abstain from such job temporarily.
4- The excessively thirsty person, who cannot withstand thirst, making fasting very difficult or impossible for him.
5- Pregnant women the fasting of whom would harm them or their baby, even if they are not about to give birth.
6- Breastfeeding women who have little milk and for whom, if they fast while breastfeeding, the fasting will cause harm or reduce their milk, thus harming their babies; in this case they must break the fast. However, if they find substitutes in artificial or animal milk or the breastfeeding of other women, whether offered voluntarily or paid for when they can afford their fees, in these cases it is not allowed to break the fast.
598. As breaking the fast is allowed for these people who are excused, fasting is allowed if they so wish and insist on withstanding the difficulty as long as they do not become harmed; but if fasting harms them in a way that cannot be ignored and which must be protected from, in this case fasting is not allowed and the ruling for the ill applies; this ruling does exclude the pregnant or breastfeeding woman the fasting of whom would harm her baby because she must protect her baby from harm to the same degree that she protects herself from it.