In illustrating the action of sunnah, it was explained before that some expressions are employed to indicate that certain commands are under the sunnah regulation. Also, as mentioned before, some one who performs what is sunnah will be rewarded.

Even though certain actions are under the category of sunnah commands, the majority of Syafi‘eyyah scholars are of the opinion that the fulfillment of sunnah actions are equally expected of Muslims as the performance of wajib (obligatory commandments). This is because Muslims who perform what is sunnah are those who are pious and obedient to Allah Subhanahu wa Ta‘ala. Besides that, the performance of sunnah actions demanded of Muslims just as the performance of wajib except that when wajib is neglected the person will be punished but this is not applicable to sunnah.

According to Arabic definition of haram, it is "something which is prohibited". The conceptual meaning of haram as given by usul fiqh scholars is:

Meaning: "Something which is demanded by Syari‘ (Allah and His Prophet Shallallahu ‘alaihi wasallam) to be avoided through definite and binding commandments."

Haram is also defined as:

Meaning: "An act in which those who perform it are punished by law and those who abstain from it are rewarded."

The first definition reveals if a practice is prohibited (haram) while the second definition deals with the consequences of performing or neglecting prohibited practices. Those who perform them are punished and those who reject them are rewarded.

The haram commandments are sometimes known as mahzhûr (prohibited), ma‘siah (offence), zanbu (sin), mamnû‘ (forbidden), qabîh (evil), sayyi’ah (immoral), fâhishah (ill-deed), itsm (sin) and mazjûr ‘anhu (blamed).

Among others, the expressions employed to indicate that the command is sunnah are as follow:

a. Through direct commands using the tahrim utterances and others from the same root as mentioned in Allah’s word that says:

Meaning: "Come not near to shameful sins (illegal sexual intercourse, etc.) whether committed openly or secretly."

c. Through the command to avoid certain immoral practices as stated in Al-Qur’an:

d. Certain deeds in which the doer is threatened with punishment either in this world or in the hereafter. This is explained by the words of Allah which say:

There are several other utterances emphasising that certain deeds are ruled as haram, for example, through the word  (Allah curses), (the wrath of Allah) and (Allah combats).

Makruh, according to Arabic terminology is ‘that which is despised’. It is also defined as ‘al-qubh’ (bad) and ‘something to be avoided’. According to the conceptual meaning of usul fiqh, makruh can be defined as:

Meaning: "Something which is demanded to be avoided by Syari‘ (Allah and His Prophet Shallallahu ‘alaihi wasallam) through a mild commandment."

It is also defined as:

Meaning: "That which is praised when neglected and not condemned (sinful) when performed."

It is obvious here that makruh is a reprehensible deed or circumstance and even though it is not sinful when done, but it is encouraged to be neglected.

In indicating the reprehensibility of certain deeds, Allah Subhanahu wa Ta‘ala has employed specific expressions that denote that the deeds are makruh. Some of them are:

a. Through the utterance of the word karâhah (reprehensible) and its synonyms as found in the hadith of the Prophet Shallallahu ‘alaihi wasallam which says:

b. The instruction to avoid and abstain certain deeds through claims of them being not haram but makruh because to avoid them is more important than to perform them, as the saying of Allah states:

According to usul fiqh scholars, the prohibition against trade transactions in this verse is ruled as makruh because the original law governing businesses and trade in Islam is mubah (permissible). It only becomes makruh because transaction is carried out during the time when Muslims should hasten in preparing themselves to perform the Jumu‘ah prayer.

Terminologically mubah means ‘permissible’, ‘allowable’ or ‘tolerated’. Conceptually, according to Al-Imam Al-Ghazali, mubah is defined as:

Meaning: "Something permitted by Allah to be done or not to be done without any specification on whether the doer will be praised or condemned and those who abstain are not praised or condemned."

According to fiqh methodology:

Meaning: "Basically, every thing is mubah (permissible)."

Based on this prinsiple, everything is allowable in the absence of evidence or ruling which proves its prohibition. Thus, the mubah ruling is independent because it is neither under the category of amr (command) nor the category of nahy (prohibition).

Nevertheless, the ruling of mubâh on certain issues is not universal or general, but relative and depends on the intention, type of action and the time of execution.

For example, eating and drinking are two actions that are ruled as mubah. A person has the choice of either doing it or avoiding it. But, if someone has chosen not to eat or drink, and his choice will cause him harm, the ruling on eating or drinking, which was originally mubâh, might change to wajib (obligatory) as it is an obligation to him to take care of his physical and mental health and for this purpose, he needs to eat and drink.

On the other hand, if someone eats and drinks to excess and this action causes him harm, then, in this case he should be prohibited from doing so as it will lead him to commit that which is forbidden by shara‘which is harming himself.

Among others, the expressions employed to indicate that certain deeds are mubâh are as follow:

a. Through the evidence which indicates that certain actions are not considered sinful as Allah says:

b. The evidence that clarifies the lawfulness of something such as it is lawful to eat edible things and good food as Allah says:

A deep understanding and a detailed interpretation of the classifications of Islamic law is of great significance to mujtahid and istinbat scholars as human actions and practices cannot be separated from any one of the rulings classified by shara‘.