Abiathar in Fausset's Bible Dictionary

("father of abundance".) The only son of Ahimelech, the high priest, who escaped the slaughter committed by Saul at Nob, on Doeg's information that Ahimelech had inquired of the Lord for David, and given him the shewbread and the sword of Goliath (1 Samuel 22). Eighty-five persons wearing the priestly linen ephod were killed. Abiathar, with an ephod (the high priest's mystic scarf) in his hand, escaped to David. It is an instance of God's retributive justice that Saul's murder of the priests deprived him thenceforth of their services in inquiring of the Lord (1 Chronicles 13:3); step by step he sank, until, bereft of legitimate means of obtaining divine counsel, he resorted to the illicit course of consulting the witch of Endor, and so filled the measure of his iniquity and brought on himself destruction (1 Chronicles 10:13). David, on the contrary, by sheltering Abiathar was enabled to inquire of the Lord in the ordained way (1 Samuel 23:6-9; 1 Samuel 30:7; 2 Samuel 2:1; 2 Samuel 5:19; 2 Samuel 21:1, an undesigned coincidence with Psalm 16:7, and so a proof of genuineness)...

Link: https://bible-history.com/faussets/A/Abiathar/