2 Then Israel made a vow to the Lord and said, "If you will indeed give this people into our hands, then we will utterly destroy their towns."

Matthew Henry's Commentary on Numbers 21:2

Commentary on Numbers 21:1-3

(Read Numbers 21:1-3)

Before the people began their march round the country of Edom, the king of Arad, a Canaanite, who inhabited the southern part of the country, attacked them in the wilderness, and took some prisoners. This was to lead the Israelites to look more thoroughly to the Lord.