Numbers 14:43

For the Amalekites and the Canaanites are there before you, their armies having probably been mobilized to resist the threatened invasion, and ye shall fall by the sword; because ye are turned away from the Lord, therefore the Lord will not be with you. Two days before, in unbelief, they had refused to take up arms against the inhabitants of Canaan, and now again, in unbelief, because they refused to accept the word of Moses concerning the seriousness of God's judgment, they intend to undertake the conquest; to the old sin of unbelieving despair came the new sin of presumptuous self-confidence.