There are important terminology in Shariah that are critical for us to understand so that we may fulfill our duties towards Allah Ta’ala and prevent ourselves from committing sin.
Fard-e-I’tiqaadi is an explicit obligatory act. It refers to a command of Shariah which is proven by the distinct evidence of Shariah (in other words by such proof that is beyond any doubt). There is Ijma (consensus of the learned Muslim scholars) that the one who denies any Fard-e-I’tiqaadi, then such a person is an absolute infidel. The one who deliberately leaves out even once, any Fard-e-I’tiqaadi such as Namaaz, Ruku and Sujood without a valid reason permitted by Shariah, is a Faasiq (a transgressor), guilty of having committed a major sin and is deserving of the torment of hellfire.
Fard-e-Amali is an implicit obligatory act. This is a command which is not explicit (as Fard-e-I’tiqaadi) but is in view of the consensus of the Mujtahideen. The command is based on the evidence of Shariah and one is regarded as guilty of transgression if it is left out, and one will not be relieved of his responsibility unless he fulfills it. When it is Fard in any Ibaadat (worship), then that Ibaadat will be regarded as invalid and nullified if that particular action is not fulfilled. To reject or deny it without a valid reason is an act of transgression and misguidance. However, if there is a person who is worthy of arguing a certain view, based on the view of Shariah (Mujtahid) then he has the right to differ on the basis of any evidence of the Shariah.
An example of this is the differences between the righteously guided A’ima-e-Mujtahideen (Imam Abu Hanifa, Imam Shafa’i, Imam Ahmad bin Hambal and Imam Malik (Radiallahu Ta’ala Anhum)), where one Imam considers something to be Fard whilst the other does not. For example, according to the Hanafi school of thought the Masah (which is to pass wet hands over the head in Wudu (ablution)) of a quarter of the head is Fard and according to the Shafa’i school of thought, even the Masah of one strand of hair is sufficient to fulfill the Fard, whilst according to the Maliki school of thought the Masah of the entire head is Fard. In Fard-e-Amali, every person should adhere to the principles of the Imam of whom he is a Muqallid (adherent). It is unlawful (impermissible) to follow any other Imam besides your own Imam without any legitimate reason of Shariah.
Waajib-e-I’tiqaadi is an explicit compulsory act. This is that which is proven as essential through Daleel-e-Zanni, which is a tradition reliably transmitted by one or a few people.
Waajib-e-Amali is an implicit compulsory act. It is that Waajib-e-I’tiqaadi that even though one does not fulfill it, there is the probability that one will be absolved of his responsibility. However, its necessity to be fulfilled is given precedence. If the Waajib-e-Amali is omitted in any Ibaadat where it is regarded as necessary to be fulfilled, then without it being done, such Ibaadat will be regarded as defective but valid. To intentionally omit even a single Waajib is a minor sin (Gunah-e-Sagheera) and to do so more than once is a major sin (Gunah-e-Kabeera).
Sunnat-e-Mu’akkadah is that practice of Rasoolullah (Sallallahu Alaihi Wasallam) which he regularly and consistently performed. Even though he regularly practiced it, he occasionally omitted it to show that this was permitted and that it is not regarded as Fard. To leave it out is Isa’at (discussed below) which is bad but less than abhorrent and to practice it is Sawaab which is deserving of reward. To miss it on the odd occasion is deserving of a warning of serious consequences and to leave it out habitually is deserving of punishment.
Sunnat-e-Ghair-Mu’akkadah is not a regular practice but deserving of reward. It is that desired action in the light of Shariah, that leaving it out is regarded as undesirable but it is not regarded as undesirable to the extent that one who omits it has been warned of receiving punishment for doing so. To practice it is to attain reward and to omit it even habitually does not incur warning of serious consequences.
Mustahab means a desirable action. This refers to that practice, which in the view of the Shariah is desirable and omitting it is not regarded to be undesirable, even though it was practiced by Rasoolullah (Sallallahu Alaihi Wasallam) himself and it was something that was encouraged or even if the Learned Scholars of Islam (Ulama) were pleased with it being practiced even though it may not have been mentioned in the Ahadith. It is worthy of reward if it is done and if it is not done then there is absolutely no accountability.
Mubah is lawful. The law regarding this is alike either if it is done or not (in other words either doing it or not doing it, are both lawful).
Haraam-e-Qata’i is that which is explicitly prohibited. This is the opposite of Fard. To intentionally carry out such an action is a major sin and transgression of the law, and to abstain from such an action is Fard, an obligation and deserving of reward.
Makrooh-e-Tahreemi is disapproved to the point of being forbidden. This is the opposite of Waajib. By committing such an action, the Ibaadat becomes defective and one who commits such an action is regarded as sinful, even though the sin of such an action is less than that of committing a Haraam (Forbidden / Prohibited) offense. The committing of such an offense on a few occasions amounts to it being regarded as a major sin (Gunah-e-Kabeera).
Isa’at is a bad action. The committing of such an action is bad and one who commits it occasionally deserves chastisement, whereas making it a habitual action causes one to be culpable of punishment. Isa’at is the opposite of Sunnat-e-Mu’akkadah.
Makrooh-e-Tanzeehi is an undesirable action. It is that action which is regarded as undesirable in the Shariah but it is not to the extent where there is warning of any punishment for committing it. This is the opposite of Sunnat-e-Ghair Mu’akkadah.
Khilaaf-e-Ula is contrary to what is best. This means to do an action, which if avoided, would have been better. However, if it is done, then there is no harm or any chastisement for it. This is the opposite of Mustahab.
May Allah Ta’ala grant us the Taufeeq to seek the knowledge of our Deen, Allahumma Ameen.
[Compiled from Bahaar-e-Shariat by Sadrush Shariah Mufti Amjad Ali Aazmi Radiallahu Ta’ala Anh]