Yahweh said to Gideon, The people are yet too many; bring them down to the water, and I will try them for you there: and it shall be, that of whom I tell you, This shall go with you, the same shall go with you; and of whoever I tell you, This shall not go with you, the same shall not go.
"Bring them down to the water"  (Judges 7:4).  God has frequently devised a "water test" in the achievement of his holy purposes.  It was a water test that selected Rebekah to be the wife of Isaac  (Genesis 24:43-46). It was the water test that separated liberated Israel from the pursuing legions of Pharaoh, and here God selected the triumphant three hundred from the ten thousand by a water test.  Even today, God chooses among the sons of men by another water test - immersion (Mark 16:15,16).