Furūʿ al-dīn (Arabic: فروع الدين), lit. branches/ancillaries of the faith, is a legal and theological term which refers to actions in Islam that have been legislated, and they are often discussed alongside the roots of faith which are known as the Usul al-din (which primarily pertain to beliefs as opposed to action). Some of the ancillaries of religion include: prayers, fasting, khums and zakat (religious taxes), hajj (pilgrimage), jihad (struggle), enjoining the good, forbidding the evil, and tawalli and tabarri.
According to the more common and famous categorizations, Islamic scholars have divided religious knowledge into three parts. They have done so inspired by a few hadiths. They are:
These two terms (i.e. usul al-din, and furu' al-din) have become very famous and commonly used, and in the history of Islamic thought have played a primary and pivotal role. However, in the Qur'an, and in both Sunni and Shi'i hadiths, we do not see any type of categorization of the "Usul" (principles) and "Furu' (ancillaries) as such. This fact shows that these two terms were simply theological terms that some theologians decided to use and establish, and it is through their usage that these categorizations became commonly used.
This being said, "It should also be noted that some hadiths have indicated that Islam has pillars and roots. However, these are scattered indications throughout the hadith literature and are not identical to the categorizations of Usul and Furu' that have become more common today.
As an example, there is a hadith from Imam al-Sadiq (a) where he was asked, "What are the pillars of religion? What are the matters that everyone must have knowledge of and that nobody should reject? Those that if somebody falls short in recognizing and learning about them, their religion will become corrupt and God will not accept their actions? And to the contrary, if somebody recognizes them, and acts according to them, their religion will be correct and in order, and their actions will be accepted?" The Imam (a) responded, "Bearing witness to the oneness of God, the prophethood of the Prophet (s), believing that which has come from God, zakat, and wilaya."
It is true that the Usul and Furu' al-din have not been mentioned specifically in verses of the Qur'an and in the traditions. However, scholars of theology and jurisprudence have searched the sources and gone through the verses of the Qur'an and the hadith literature, and from this, they have derived Usul and Furu' al-din in order to educate the general population about them.
According to what has become more commonly known, furu' al-din i.e. ancillaries of the faith include the following:
It is possible that specifically naming these ten items is because of the vast importance given to them in verses of the Qur'an and in the hadiths. However, it should be noted that the ancillaries and rules of religion are not limited to those listed here. They also include things that have not been mentioned, like rulings about selling and purchasing, marriage, hadd and ta'zir, blood money, judgment etc.
Some of the ancillaries of religion are associated with the connection between God and mankind, and have been presented in the form of rulings and legislation. These are responsibilities that one must carry out for his sake, and include responsibilities like prayers, fasting, and hajj. Some of these responsibilities include things which people have responsibilities towards each other and regulate human society. This includes ancillaries like jihad and khums.
Unlike usul al-din, the ancillaries of the faith are a group of matters in which, if one falls short in carrying them out or alternatively, overemphasizes or overdoes them, it will not really hurt the religion of Islam. However, even if one does not reject them entirely, and does not act according to them, it can cause corruption and mischief, and as such, adherence to these ancillaries of religion, like its roots, is obligatory. On the other hand, the roots of religion are a group of beliefs upon which the religion of Islam is based without which it is impossible for one to be a Muslim. Moreover, rejecting even one of these roots is enough to qualify a person as a disbeliever. However, with regards to carrying out the obligations of Islam, Muslims are not homogeneous. Some are extremely devout and do their best to carry out all of their obligations and to be loyal to the laws and regulations of Islam. Others, however, are less concerned with being devout and they do not carry out some of their obligations.
A person who is mukallaf must either (1) reach the stage of ijtihad and follow their own rulings, i.e. they should be knowledgeable enough to derive the laws by themselves or (2) practice caution in their actions in order to avoid any possible forbidden action or (3) do taqlid from another mujtahid.
The fields of jurisprudence and the principles of jurisprudence are two fields of study in Islam which respond to mankind's questions about the ancillaries of religion. In fact, these are the two fields of study which clarify what one's responsibility is in action. Through these two fields of study, Shi'a jurists derive the ancillaries of religion and clarify the laws and regulations of Islam.
The sources that jurists use to derive and clarify the laws of Islam are the following:
There are several differences between the roots and the ancillaries of religion. These include the following points: