It has been established in Islamic law that one of the conditions obligating fasting is the legal and physical ability to endure it. The legal ability refers to the absence of any legal impediments that prevent fasting and these include menstruation and post-natal bleeding. The physical ability is the physical energy of a person. This means that a person must not suffer from an illness that causes extreme hardships during his fast, nor old age that makes a person tantamount to an ill person who cannot fast, or a traveler since traveling is presumably a difficult undertaking. The Prophet (peace and blessings be upon him) said, “Travel is a portion of torment; it denies you your food, drink, and sleep” (recorded by Bukhari and Muslim).
Probability is given the same status as certainty. Out of God’s mercy and the ease afforded by the munificent Islamic law, travel lifts the obligation of fasting even if it does not involve hardship.
Included under physical ability is strenuous work which a person cannot forsake during the fasting hours of Ramadan due to his needs or those of his dependents. It is not obligatory for a Muslim for whom fasting is obligatory to fast during the daylight hours of Ramadan if he cannot postpone his work until after the month of Ramadan or if it is not possible for him to work nights. This is because he must work to meet his expenses or those of his dependents. Examples include laborers, porters and the like, especially those who work under extreme heat conditions or for long hours.
In Mawahib Al-Jalil Sharh Mukhtasar Khalil [2/441], the erudite Maliki scholar Al-Hattab cites Al-Burzuliy as saying, “The ruling for exposure to flax dust, coal dust, and dust generated in barley and wheat stores is the same as that for exposure to gypsum dust.” He continued saying, “Based on this, the question posited in our times concerns fasting during summertime and whether it is permissible for a paid harvester to refrain from fasting. The legal opinion in our school is that it is permissible if the work is indispensable for his livelihood; otherwise, it is disliked."
There is no contention over the permissibility for a crop owner harvesting his own crops even if this will cause him to break his fast or else he would commit the prohibition of wasting his wealth. The same applies to women who spin linen and thin thread with their mouths. It is generally permissible for them to refrain from fasting if their work involves spinning linen which leaves an aftertaste in the mouth. But if it does not leave an aftertaste, then it would be disliked to refrain from fasting. In case if women working in spinning are physically weak or in a poor condition financially which makes them in a dire need to work, then it is permissible for them to refrain from fasting.
This ruling is the same as that for males who do strenuous work i.e. it is permissible for them to refrain from fasting if they are weak. But if they do not need to work, their work is considered disliked during the fasting hours of Ramadan.”
Making the intention
Those working in strenuous jobs should make the intention to fast at night. They are not to refrain from fasting except on the days on which they are most certain to engage in strenuous work which, through previous experience, know will cause them hardship while they are fasting. This is because a probability is given the same status as a certainty.
Shaykh Al-Bayjuri wrote in his meta-commentary on Fat-h Al-Qareeb Li Ibn Qasem Sharh Matn Abu Shuja (1/314), “An ill person, whose illness is chronic, may refrain from making the intention at night. But a person whose illness is not chronic, such as one who suffers from intermittent fever and who at the time of making the intention has a fever, may omit making the intention at night.
Otherwise, he must make the intention because the excuse ceases to exist at the time when he must make it. The same applies to harvesters, farmers, millers and the like — they are to make the intention at night and if they later need to break their fast, they may do so.”
Based on this and in reference to the question, it is permissible for the farmers in your country to refrain from fasting if they work in extremely hot weather or work long days during which they cannot fast except with difficulty. This is likewise permissible if they cannot postpone their work until nightfall or after the end of Ramadan. In such a case, they must make the intention to fast at night and, if they wish, refrain from fasting on the days on which they are certain that they will engage in work that will impede their fast. However, they must make up their missed fast days after the month and, if possible, before the next Ramadan.
God the Almighty knows best.