Judges 7:4
And the LORD said unto Gideon, The people are yet too many; bring them down unto the water, and I will try them for thee there: and it shall be, that of whom I say unto thee, This shall go with thee, the same shall go with thee; and of whomsoever I say unto thee, This shall not go with thee, the same shall not go.
Judges 7:4 belongs to the repeated story of backsliding and chastisement followed by confession and deliverance, in which the Lord raised up faithful and valiant men to put down idolatry and to deliver Israel from enemies, yet when the deliverer died and the people were released from his authority they gradually returned to their idols. In its immediate setting it belongs to Gideon's deliverance of Israel from Midian, which followed a period of oppression and the people's confession of their sins, when God raised up Gideon to help His people. God said the people were still too many and commanded Gideon to bring them down to the water, where God Himself would test them and decide of each person whether he should go with Gideon or not. The selection was God's, and the ensuing victory over Midian came through the small group He chose, not through Israel's strength.
In the test the three hundred who scooped up water with their hands and drank as they went were selected, while those who stopped to drink at ease and leisure were sent home. Those who stopped to drink leisurely were sent home, and those who stayed ready to advance, scooping up water as they went, were chosen. Their conduct separated those who stayed alert and controlled their own needs from those who stopped to drink at ease, for the three hundred would not let their wants hinder their duty. The way they drank revealed fitness for the emergency: alertness, self-control, readiness to advance and to put duty before personal wants and needs, along with courage, faith, and freedom from defilement with idolatry, so that God could direct and use them to deliver Israel. These were qualities needed in an emergency, and because they had not defiled themselves with idolatry God could direct them and use them.
God deliberately reduced the numbers and chose simple means so that no person, people, or leader could claim the glory for human strength, skill, wisdom, or numbers. The Lord alone was to be exalted as Israel's source of strength, to rebuke pride and self-reliance, showing that He can save by few as well as by many and is honored by the character rather than the number of those who serve Him. The victory over Midian therefore came not through numbers or the most talented workers but through God's power, wisdom, and help working with human effort. It was received by living faith, humble trust, whole reliance on Him, surrender to Jesus, and obedience in following His special directions, while faithlessness and narrow plans accomplish very little. God accomplishes great things through weak people who rely wholly on Him, walk in humility, and surrender themselves to Jesus.
The deliverance showed that God was Israel's true ruler, even though the people wanted divine authority visibly embodied in a human king. Applied to workers, the testing and reduction means that only those committed to the work's central purpose and fit for the battle should hold positions of responsibility, and those who are not should not be kept in them.