1 Samuel 30:6-10

6David was very upset, for the men were thinking of stoning him; each man grieved bitterly over his sons and daughters. But David drew strength from the Lord his God.

7Then David said to the priest Abiathar son of Ahimelech, “Bring me the ephod.” So Abiathar brought the ephod to David.

8David inquired of the Lord, saying, “Should I pursue this raiding band? Will I overtake them?” He said to him, “Pursue, for you will certainly overtake them and carry out a rescue!”

9So David went, accompanied by his six hundred men. When he came to the Wadi Besor, those who were in the rear stayed there.

10David and four hundred men continued the pursuit, but two hundred men who were too exhausted to cross the Wadi Besor stayed there.