Philistines came up and spread out in the Valley of Rephaim. David inquired of the Lord

2 Samuel 5:17-25

Now the Philistines had come and spread out in the Valley of Rephaim; so David inquired of the Lord, “Shall I go and attack the Philistines? Will you deliver them into my hands?” The Lord answered him, “Go, for I will surely deliver the Philistines into your hands.”

So David went to Baal Perazim, and there he defeated them. He said, “As waters break out, the Lord has broken out against my enemies before me.” 

Once more the Philistines came up and spread out in the Valley of Rephaim; David inquired of the Lord, and he answered, “Do not go straight up, but circle around behind them and attack them in front of the poplar trees. As soon as you hear the sound of marching in the tops of the poplar trees, move quickly, because that will mean the Lord has gone out in front of you to strike the Philistine army.” So David did as the Lord commanded him, and he struck down the Philistines all the way from Gibeon to Gezer.

Why?

David's war was not David's fighting against the Philistines, but the Lord helped him and struck the Philistines before David went on.

Doing important things, or making important decisions should inquire of the Lord. But most of us may not know which one is the way the Lord gives us. Or We can't hear the voice of the Lord, we may had the way and asked the Lord, so we may not hear the word of the Lord.

How?

Come closer to the Lord and hear the voice of the Lord, when important things need to inquire the Lord we may identify which is the word of the Lord.