Allah (swt) reveals a rule and provides a legal reason or cause(Illah). In this case, when a new situation arises that carries the same Illah, then the original rule can be extended to the new issue.

Why is it said that Ibadats (rituals) are not reasoned?

Firstly let us provide a context for this discussion. When we talk about the reason for something we mean the Shar'ii Illah (divine reason). That is the reason Allah (Subhanahu wa ta'aala) gave for why He (subhanahu wa ta'aala) legislated the rule. The short of it is the matters pertaining to the Ibdaat (worships), Morals, Clothing and foodstuffs have not been accompanied by an Illah for us. So for example Rasool Allah (sallAllahu alaihi wasallam) said: ''Khamr (intoxicants/alcohol) has been forbidden for itself.'' Therefore someone cannot argue that Khamr intoxicates and that is the Illah, otherwise it would be allowed to drink drinks which contain 5% alcohol content as long as you didn't drink enough to intoxicate, this is incorrect as even o­ne drop of alcohol intentionally consumed is a sin. In the absence of the Illah in these areas many began to concoct them in order to justify why Allah allowed women to wear silk but forbade man, or why men are not allowed to wear gold why women can adorn it. This is a dangerous mentality to possess because the absence of the illah (reason) leads to the absence of the rule. So some say that man cannot wear silk because it is contrary to the reason for the rule, which they determine is modesty. But if in a society everyone wears silk, and therefore wearing silk is no longer seen to be immodest, then the rule could be deemed to no longer exist, but this is completely incorrect. Some also say that the Illah for fasting is to remove the toxins from the body and therefore the Illah is its benefit to the health of the person. But what if eminent doctors agree that it is harmful to the body, would we stop fasting? No because we fast for Allah's sake alone as an act of worship. If we try to concoct an Illah (reason) we are trying to comprehend the intentions of Allah na'uzubilla, may Allah save us from this mentality, how can human beings determine the intentions of the legislator unless he (subhanhu wa ta'aala) informed us of this in the Qur'an or through His Rasool. For example Rasool Allahsaid in a Hadith ''Muslims are partners (associates) in three things: in water, pastures and fire''. This Hadith did not include Illah (reason), and this could imply that these three things are the only ones which represent public property with no consideration given to their depiction for the community's need for them. However, if one scrutinised the issue he would find that the Prophet allowed the possession of water in At-Taif and Khaybar by individuals, and they actually possessed it for the purpose of irrigating their plants and farms. Had the sharing (association) of water been just because it is water and not because of the consideration of the community's need for it, then he would not have allowed individuals to possess it. So from the saying of the Prophet , ''Muslims are partners (associates) in three things: in water, pastures and fire'' and from his permission to individuals to possess the water, it can be deduced that the Illah (reason) of partnership in the water, pastures and fire, is their being of the community utilities that are indispensable to the community. So the Hadith mentioned the three (things) but they are reasoned as being community utilities. Therefore this Illah (reason) goes along with the reasoned (rule) in existence and in absence. So anything that qualifies as being of the community utilities (roads, hospitals, parks, universities. .etc) is considered a public property, whether or not it was water, pasture or fire i.e. whether it was specifically mentioned in the Hadith or not. If it ceased to be of the community utilities, even if it was mentioned in the Hadith like the water it would not be a community utility, it would rather be of the things which can be possessed individually. The criteria for determining things to be a public utility is that it is anything which, if not available to the community, whether the community was a group of bedouins a village, city, or a State, would cause them to disperse in search of it, then it would be considered of the community utilities, like the water sources, forests of firewood, pastures of livestock and the like.