1 Samuel 30:6-10

Also, David was in great distress because the people spoke of stoning him, for all the people were embittered, each one because of his sons and his daughters. But David felt strengthened in the Lord his God.

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

And David inquired of the Lord, saying, “Shall I pursue this band of raiders? Will I overtake them?” And He said to him, “Pursue, for you will certainly overtake them, and you will certainly rescue everyone.”

So David left, he and the six hundred men who were with him, and they came to the brook Besor, where some who were left behind stayed.

But David pursued, he and four hundred men, for two hundred who were too exhausted to cross the brook Besor stayed behind.