Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
To the cave Adullam - Or rather "of Adullam." Adullam was the name of a town of Judah in the "Shephelah," not far from Bethlehem, and below it. Innumerable caverns, one nearly 100 feet long, are excavated in the soft limestone hills in the neighborhood of Beit-Jibrin. (The cave is placed by Ganneau and Conder on the hill (500 feet high) over 'Aid el Ma or Miyeh.) David's brethren and kinsmen joined him partly from sympathy with him, and partly because their own lives were in jeopardy front Saul's furious enmity.
Discontented - See the margin. (Compare Sa1 30:6; Sa2 17:8.) The phrase here denotes those who were exasperated by Saul's tyranny.
Mizpeh of Moab - A good conjecture connects it with "Zophim" (a word of the same root as Mizpeh) on the top of Pisgah Num 23:14. It is probable that David's descent from Ruth the Moabitess may have had something to do with his seeking an asylum for Jesse, Ruth's grandson, in the land of her birth. It would be very easy to get to the Jordan from the neighborhood of Bethlehem, and cross over near its embouchure into the Dead Sea.
Come forth, and be with you - The construction of the Hebrew is very strange. The Vulgate, Syriac, and Arabic seem to have read "dwell" instead of "come forth."
He brought them before ... - The Septuagint renders it "he persuaded (the face of) the king."
In the hold - Where David was after he left the cave of Adullam, probably in the land of Moab.
The phrase "all the while," would indicate that David sojourned a considerable time in Moab.
The prophet Gad - Mentioned here for the first time. One may conjecture that Samnel had sent him privately from Naioth to tell David not to abide in the hold. Whether he stayed with David or returned to the College of the prophets does not appear. For later notices of him see marginal references.
The forest of Hareth is unknown.
Under a tree in Ramah - Rather, "under the tamarisk-tree on the high place," where he always held such meetings. It was a kind of parliament in the open air, and all his tribesmen gathered round him. (Compare Jdg 4:5.)
Ye Benjamites - Showing how isolated the tribes still were, and how for the most part Saul was surrounded by his own tribesmen only.
He inquired of the Lord ... - This was not true, but Ahimelech's going to fetch the sword from behind the ephod might have given occasion to the belief on Doeg's part that he had put on the ephod to inquire of the Lord for David.
Goeth at thy bidding - Better, "has access to thy (private) audience," or council (compare Sa2 23:23, margin).
Did I then begin ... - Some lay the stress upon the word "begin," as though Ahimelech's justification was that he had often before inquired of the Lord for David when employed on the king's affairs. But it is much better to understand the words as Ahimelech's solemn denial of having inquired of the Lord for David, a duty which he owed to Saul alone as king of Israel. The force of the word "begin" lies in this, that it would have been his first act of allegiance to David and defection from Saul. This he strenuously repudiates, and adds, "thy servant knew nothing of all this" conspiracy between Jonathan and David of which Saul speaks: he had acted quite innocently.
We are not to suppose that Doeg killed them all with his own hand. He had a band of men under his command, many or all of whom were perhaps foreigners like himself, and very likely of a Bedouin caste, to whom bloodshed would be quite natural, and the priests of the Lord of no more account than so Early sheep or oxen.
Both men and women ... - The language employed in the case of the Amalekites Sa1 15:3 and of Jericho Jos 6:21. Nothing could be more truculent than Saul's revenge.
Abiathar - He may have remained at Nob to take care of the sanctuary when the other priests went to Saul, and so escaped. He continued David's faithful friend throughout his reign Sa1 23:9; Sa1 30:7; Sa2 15:24, Sa2 15:29, Sa2 15:35, but gave offence by taking Adonijah's part against Solomon Kg1 1:7, Kg1 1:19, Kg1 1:42, and in consequence was deprived of the high priesthood Kg1 2:26-27. In Mar 2:26, he is spoken of as the High Priest who gave the showbread to David. Perhaps he was the instigator of this act of kindness to David; and for this cause, as well as his constancy to David, is mentioned by our Lord instead of Ahimelech. It is also possible that, as sagan to his father, he may have performed most of the priestly functions, as Hophni and Phinehas did in the lifetime of Eli. Abiathar did not actually join David until he went to Keilah (marginal reference).
The characteristic generosity of David's disposition breaks out in these words. He never forgot a friend. (Compare Sa2 1:26; Sa2 9:1, etc.) David acknowledges that Saul's enmity against Abiathar is the consequence of his enmity against himself, and therefore David makes common cause with him.