Joshua 9 contains a fascinating narrative about the a ploy hatched by the inhabitants of Gibeon to fool Joshua into a a peace treaty. After the ambassadors of Gibeon arrive looking as if they had traveled from a great distance, they convince the people of Israel (to include Joshua) that they were not in fact people of the promised land. Joshua was waring against those living in the promised land under the orders of God, but these people played themselves off as potential neighbors. The problem however, is that they started out with bad provisions and worn out sandals in an attempt to fool Joshua and it worked.
Verse 14 contains the lesson of this narrative. It reads, "So the men took some of their provisions, but did not ask counsel from the LORD" (Joshua 9:14, ESV). It looks as if the Israelites sampled some of this bad bread from themselves and were convinced. Some commentators content that they may have even shared a meal with the bad provisions as a part of this pact. Using the false provisions provides a parallel for the poor agreement but more significantly is the second part of this sentence, "but [they] did not ask counsel from the LORD." They did this under their own power without praying about this serious decision.
It is a good picture for us today. We should be consulting with God, that we would work and act in accordance with his will rather than our own. James writes that we should ask for wisdom (James 1:5), something that was clearly lacking in the Joshua account.