Passage
So Israel made a vow to Yahweh and said, “If You will indeed give this people into my hand, then I will devote their cities to destruction.”
Numbers 21:2 (LSB)
Nearby Context
Numbers 21:1 Then the Canaanite, the king of Arad, who lived in the Negev, heard that Israel was coming by the way of Atharim, and he fought against Israel and took some of them captive.
Numbers 21:2 So Israel made a vow to Yahweh and said, “If You will indeed give this people into my hand, then I will devote their cities to destruction.”
Numbers 21:3 Then Yahweh heard the voice of Israel and gave the Canaanites over; so they devoted them and their cities to destruction. Thus the name of the place was called Hormah.
Numbers 21:4 Then they set out from Mount Hor by the way to the Red Sea, to go around the land of Edom; and the people became impatient on the way.
Study Lenses
The verse centers on "israel", "yahweh", "said", "indeed", "give", "people", "hand", and "devote". It is saying that the verse draws attention to "israel" and "yahweh", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "Then the Canaanite the king of Arad..." into verse 3's "Then Yahweh heard the voice of Israel...", so "israel" and "yahweh" belong inside that flow. In Numbers context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "israel" and "yahweh" with trust shaped by these words, not by a vague optimism outside the passage.