John Gill Commentary 1 Samuel 30:7

"And David said to Abiathar the priest, the son of Ahimelech, I pray thee, bring me hither the ephod. And Abiathar brought thither the ephod to David." — 1 Samuel 30:7 (ASV)

And David said to Abiathar the priest, Ahimelech's son
The son of Ahimelech, who was slain at Nob by the order of Saul, (1 Samuel 22:19); and Abiathar his son, who fled to David with the ephod, on the death of his father, (1 Samuel 22:20), was now high priest in his room; and who it seems was with David when he went with Achish, and returned with him; for had he been left at Ziklag, he and his ephod, in all probability, had been carried off by the Amalekites, unless we can suppose him under the protection of a special providence: it is much David had not inquired of the Lord by him about his going with Achish; perhaps the present disaster brought to mind that neglect, and made him the more diligent now:

I pray you, bring me hither the ephod ;
not to put it on himself, but that the high priest might put it on, and inquire by it before him of the Lord:

and Abiathar brought thither the ephod to David ;
for the sake of David, that inquiry might be made before him of the Lord by Urim and Thummim.