Judges 20:29,30

Israel set liers in wait Though they were assured of the success, by a particular promise, yet they did not neglect the use of means; as well knowing that the certainty of God's promises doth not excuse, but rather require, man's diligent use of all fit means for the accomplishment of them. The children of Israel That is, a considerable part of them, who were ordered to make the first attack, and then to counterfeit flight, to draw the Benjamites forth from their strong hold. See Judges 20:32.