Charles Ellicott Commentary 1 Samuel 28:6

"And when Saul inquired of Jehovah, Jehovah answered him not, neither by dreams, nor by Urim, nor by prophets." — 1 Samuel 28:6 (ASV)

And when Saul enquired of the Lord. — The question has been asked: How was the inquiry made? Since the massacre at Nob, the high priest, or at least the priest in possession of the sacred ephod and the breastplate, with the Urim and Thummim, was, we know, in David's camp, and we will soon hear of a solemn use being made of the sacred gems (See 1 Samuel 30:7–8). It has been suggested by eminent biblical scholars that after the murder of Ahimelech and Abiathar's flight to David, Saul removed the national Sanctuary from desecrated Nob and established it at Gibeon. There, during the first year of David’s reign, we find the Tabernacle, with Zadok, son of Ahitub, of the house of Eleazar, acting as high priest—probably placed in that office by Saul.

This would account for the frequent reference in David's time to two high priests, Zadok and Abiathar: Zadok, the high priest appointed by Saul, for a considerable period alone in charge of the Tabernacle; and Abiathar, who fled from Nob with the ephod and the sacred Urim, acknowledged by David as high priest, when the kingdom was eventually restored under one head. These two seemed to have divided the honors and responsibilities of the high priesthood (See 2 Samuel 8:17; 2 Samuel 15:24; 2 Samuel 15:29; 2 Samuel 15:35; 1 Chronicles 15:11; 1 Chronicles 18:16).

This Zadok, we may assume, “enquired” for Saul: some suppose by means of an ephod made in imitation of the ancient breastplate with the Urim in Abiathar's possession; but, as may be readily imagined, no response was received. It is also likely enough that some “prophets”—so called—trained, not improbably, in Samuel's school, were present with Saul. These, too, of course, received no Divine message, either by voice or in dreams.