Ijma' is the agreement of the qualified scholars of an era on a ruling. Scholars who accept it as a source cite among other evidences the verse 4:115 and reports that the community is protected from agreeing on error, and they discuss how it can be established after the generation of the Companions. Qiyas is reasoning by analogy: extending the ruling of a text to a new case that shares the same underlying reason (illa). For example, the Qur'an forbids wine (5:90), and scholars extended the prohibition to other intoxicating drinks because the reason is intoxication. Qiyas has four parts: the original case (asl), the new case (far'), the shared reason (illa) and the ruling (hukm). Not all scholars accept every source in the same way: the Zahiri school, for instance, rejected qiyas and held to the apparent meaning of the texts.