Some commentators claim that Abiathar joined David only after he was in Keilah. In this case, the narrative events of 1 Samuel 22:6 – 23:6 are not chronological but simultaneous; the deliverance of Keilah taking place at the same time as the slaughter of Nob.1 Though this is a possibility, most commentators and Bible translators understand that Abiathar was with David before David went to Keilah.
6 When Abiathar the son of Ahimelech had fled to David to Keilah, he had come down with an ephod in his hand.