Joshua 7:2-3

2Now Joshua sent men from Jericho to Ai, which is near Beth-aven, east of Bethel, and said to them, “Go up and spy out the land.” So the men went up and spied out Ai.

3Then they returned to Joshua and said to him, “Do not make all the people go up [to fight]; have only about two thousand or three thousand men go up and attack Ai; do not make the entire army go up there, for they [of Ai] are few.”