Book of Numbers twelve princes, one of each tribe. The majority of modern biblical scholars believe that the Torah (the books of Genesis, Exodus, Leviticus, Numbers, and Deuteronomy) reached its present form in the post-Exilic period (i.e., after c.520 BCE), based on pre-existing written and oral traditions and "contemporary geographical and demographic details but even more importantly from contemporary political realities". The five books are often described as being drawn from four "sources" - schools of writers rather than individuals - the Yahwist and the Elohist (frequently treated as a single source), the Priestly source and the Deuteronomist. There is ongoing dispute over
Leviticus 19 (26-36) and a general instruction to obey all of God's commands (37). The laws of Leviticus 19 are put in no obvious order, and as a result scholars tend to think that the chapter includes a collection of regulations from various sources. The practice of leaving a portion of crops in the field for poor people or foreigners to use, mentioned in verses 9 and 10, reappears in the second chapter of the book of Ruth. In Judaism, the whole chapter is part of the weekly Torah portion (parashah) "Kedoshim" () which comprises Leviticus 19:1-20:27. Leviticus 19 Leviticus 19 is