1 Samuel 14:9-11

If they say thus unto us, Tarry until we come to you; then we will stand still in our place, and will not go up unto them. But if they say thus, Come up unto us; then we will go up: for the LORD hath delivered them into our hand: and this shall be a sign unto us. And both of them discovered themselves unto the garrison of the Philistines: and the Philistines said, Behold, the Hebrews come forth out of the holes where they had hid themselves.