Ephod is used in this context as a shorthand designation for the breastplate of the high priest that contained the Urim and the Thummim. The breastplate was attached to the ephod (garment) of the high priest (Exodus 28:4–14).1 Though not always stated, we should assume that the practice of inquiring from the LORD was a regular operating protocol of David throughout his reign as king.2
9 David knew that Saul was plotting harm against him. And he said to Abiathar the priest, “Bring the ephod here.”