Some Lessons from Jurisprudence (Fiqh)
If a person swears to do a certain thing, the doing of that which he has sworn to do becomes obligatory for him. One condition is that the vow is in the Name of God. Therefore, a vow made in the name of the Prophet or of an Imam or the Quran, is not binding on him according to the Divine Law. Another condition is that what he vows to do is ruled as permissable in the Shari'ah, so a vow to do something that is ruled as forbidden (haram) or repulsive (makruh), is meaningless and not at all binding. A legitimate vow would be like one swearing to study a certain beneficial book from beginning to end, or swearing to brush one's teeth at least once a day. The breaking of such a vow necessitates a fine (kafarah).
The Book of Taking an Oath (nathr)
Nathr is a type of undertaking to do something that involves an oath but no special contract. If, for example, one makes an oath to pray all the daily nafilah prayers, i.e. the encouraged prayers that accompany the obligatory prayers of the day, all one has to do is declare that one will pray the nafilah prayers. As we saw, one of the condition of the ayman vows was that the object of the vow be not forbidden (haram) or repulsive (makruh), so that there is no obstacle to the vow being simply permissable. The condition of nathr, however is that the object of the vow be useful in some way. So any nathr to do something or to refrain from something which is not beneficial, meaning that the doing and the refraining from the action in question, are both equal, is void. As in the ayman vows, the breaking of a nathr warrants a fine.
The inner meaning of ayman and nathr, and of the necessity of acting in accordance to them, lies in the fact that both are types of compact with God, and, in the same way that one must respect one's compacts with the creatures of God ("O you who believe, be loyal to your compacts". 15:1]), so is one to respect one's compacts with God Himself. An ayman or a nathr is normally made when one has little confidence in one's willpower. By means of the ayman or nathr one makes a thing obligatory for oneself until one is able to form the desired habit. 
Lesson Seven: Laws
The ninth section of the four sections of jurisprudence consists of the issues grouped under the heading of 'laws' (ahkam). This word used here has no special definition. The fact is that those issues of jurisprudence that do not fall into one of the other three groupings have been grouped together to form this one. This section contains twelve books:
The Book of Hunting and Slaughtering (sayd and thibh)
First it is necessary to state that the meat of permitted meat animals becomes permitted either when the animal is slaughtered in a special way (thibh or nahr), or, if the animal is a wild animal the meat of which is permitted, when it is properly hunted by specially trained dogs or my means of an iron missile (like a sharp arrowhead or a sharp bullet).
The meat of tame permitted-meat animals is not permissable to eat if they are hunted, and they must be slaughtered in exact accordance to the Shari'ah. The way of slaughtering most tame animals, like hens, sheep and cows, etc., is called thibh and the way of slaughtering camels is called nahr. There is a slight difference between the actual acts of nshr and thibh, but the conditions, such as the slaughterer being a Muslim, and killing the animal in the Name of God, are the same.
Hunting is related to permitted meat animals that are wild, like deer and mountain goats, etc If the means by which the animal is hunted is a dog, the dog must be so trained that it will do whatever it is commanded, and thus reflect its master's will, and the meat of permittedmeat animals that are hunted and killed by dogs that are not trained in this way must not be eaten. In the same way, hunting with animals other than dogs, like hawks, is also not permissable.