In Islamic jurisprudence, qiyas ( , "analogy") is the process of deductive analogy in which the teachings of the hadith are compared and contrasted with those of the Quran, in order to apply a known injunction (nass) to a new circumstance and create a new injunction. Here the ruling of the Sunnah and the Quran may be used as a means to solve or provide a response to a new problem that may arise. This, however, is only the case providing that the set precedent or paradigm and the new problem that has come about will share operative causes (, ʿillah). The ʿillah is the specific set of circumstances that trigger a certain law into action. An example of the use of qiyās is the case of the ban on selling or buying of goods after the last call for Friday prayers until the end of the prayer stated in the . By analogy this prohibition is extended to other transactions and activities such as agricultural work and administration. Among Sunni Muslims, Qiyas has been accepted as a secondary source of Sharia law along with Ijmāʿ, after the primary sources of the Quran, and the Sunnah. Sunni interpretations Late and modern Sunni jurisprudence regards analogical reason as a secondary source of Islamic law along with binding consensus, following the Quran, and prophetic tradition. While Muslim scholarship in the later period traditionally claimed that analogy had existed in Islamic jurisprudence since their religion's inception, modern scholarship generally points to Muslim scholar Abu Hanifa as the first to incorporate analogical reason as a secondary source of law. Since its inception, analogical reason has been the subject of extensive study in regard to both its proper place in Islamic law and its proper application. Validity as a source of law Among Sunni traditions, there is still a range of attitudes regarding the validity of analogy as a method of jurisprudence. Imam Bukhari, Ahmad ibn Hanbal, and Dawud al-Zahiri for example, rejected the use of analogical reason outright, arguing that to rely on personal opinion in law-making would mean that each individual would ultimately form their own subjective conclusions. Bernard G. Weiss, one of today's foremost experts on Islamic law and philosophy, explains that while analogical reason was accepted as a fourth source of law by later generations, its validity was not a foregone conclusion among earlier Muslim jurists. Thus, while its status as