Joshua was a Godly man, well schooled in the ways of the Lord. Even in his young years, he often remained behind at the “tent of meeting” with the Lord even after Moses left (see Exodus 33:11). He was God’s chosen successor to Moses, and Israel committed to following him.
After years of following hard after the Lord, on one day, Joshua and his leaders considered only the natural surroundings, and used their human wisdom to make a decision. That one decision caused great turmoil in the ranks of Israel, causing “the whole assemble” to grumble “against the leaders” (Joshua 9:18).
What had happened? The near-by tribe of the Gibeonites, fearing Israel, tricked Joshua and his leaders into thinking they were from a far distance. Their worn-out sacks and old wineskins, cracked and mended, their patched sandals, old clothes and molded bread convinced Joshua that they were indeed from a distance. But he neglected to inquire of the Lord!
Natural wisdom is never enough. Inquire of the Lord before you act!