Deut.

The Book of Deuteronomy (from Ancient Greek: Δευτερονόμιον, Deuteronómion, "second law"; Hebrew: דְּבָרִים‎, Devārīm, "[spoken] words") is the fifth book of the Torah (a section of the Hebrew Bible) and the Christian Old Testament. The Hebrew title is taken from the opening phrase Eleh ha-devarim, "These are the words...". The English title "Deuteronomy" comes from the Greek deuteronomion, meaning "second law", taken from the Septuagint's (Greek) phrase to duteronomion touto, "this second law", in Deuteronomy 17:18. This Greek phrase is itself a mistranslation of the Hebrew mishneh haTorah hazoth, "a copy of this law".

The book consists of three sermons or speeches delivered to the Israelites by Moses on the plains of Moab, shortly before they enter the Promised Land. The first sermon recapitulates the forty years of wilderness wanderings which have led to this moment, and ends with an exhortation to observe the law (or teachings), later referred to as the Law of Moses; the second reminds the Israelites of the need for monotheism and observance of the laws (or teachings) he has given them, on which their possession of the land depends; and the third offers the comfort that even should Israel prove unfaithful and so lose the land, with repentance all can be restored.

Traditionally seen as the words of Moses delivered before the conquest of Canaan, a broad consensus of modern scholars see its origin in traditions from Israel (the northern kingdom) brought south to the Kingdom of Judah in the wake of the Assyrian conquest of Aram (8th century BC) and then adapted to a program of nationalist reform in the time of Josiah (late 7th century BC), with the final form of the modern book emerging in the milieu of the return from the Babylonian captivity during the late 6th century BC. Many scholars see the book as reflecting the economic needs and social status of the Levite caste, who are believed to have provided its authors.

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