Numbers is a continuation of Exodus, recording the stay of the Israelites in the wilderness of Sinai until their arrival in Moab. The title of the book is derived from the two numberings of the people recorded here.

Numbers 8

8:19 And I have given the Levites as a gift to Aaron and to his sons from among the children of Israel, to do the service of the children of Israel in the tabernacle of the congregation, and to make an atonement for the children of Israel: that there be no plague among the children of Israel, when the children of Israel come nigh unto the sanctuary.