1 Samuel 30:6-9
English Standard Version
7And David said to Abiathar the priest, the son of Ahimelech, "Bring me the ephod." So Abiathar brought the ephod to David.
8And David inquired of the Lord, "Shall I pursue after this band? Shall I overtake them?" He answered him, "Pursue, for you shall surely overtake and shall surely rescue."
9So David set out, and the six hundred men who were with him, and they came to the brook Besor, where those who were left behind stayed.