The phrase “chapter and verse” is an old English saying that means a speaker or writer is able to back up a statement or opinion with precise facts and details and can cite a reference of authority or an accepted expert on the topic. The phrase is sometimes used as “to quote chapter and verse.” In this instance, the speaker or writer quotes the law, rule, or scripture that backs up the statement and provides a reference, such as page number, so that listeners or readers can check the source to ensure it is as the speaker or writer stated.
The idiom “chapter and verse” dates back to the 1600s. During this time in Britain, the Bible was considered as the authority on all topics. By this time, the Bible had been organized into chapters and verses to help readers and students find passages of scripture and cite passages. A speaker or writer would back up a statement by quoting a scripture and then citing the book of the Bible where it could be found, along with the chapter and verse numbers.
Likely coming into literal usage about 1620, the phrase is used in writings from the 17th century to literally ask for Biblical authority in backing up a statement. It passed into figurative use by the 19th century. By the 19th century, most people would have understood that in asking for chapter and verse, a speaker was requesting an authoritative source to back up information.
In modern usage, the idiom is not often used to indicate a reference to scripture, but is more likely to be used to describe someone’s thorough knowledge of a topic and where the authority is published that can back up that knowledge. If two people are disagreeing about a topic, one person may ask the other to give the chapter and verse that supports that opinion. The person could be asking for a Biblical reference, but is more likely asking for an accepted reference from a secular authoritative source, assuming the discussion is not religious in nature.
A related idiom is “by the book,” which also refers to the Bible as the ultimate authority. The phrase “by the book” came into usage about the same time as “chapter and verse” and refers to taking action according to the Bible’s instruction. Today, this idiom may be used to refer to taking action according to any authoritative source’s instruction.