I Samuel 22:21 Midrash

וַיַּגֵּ֥ד אֶבְיָתָ֖ר לְדָוִ֑ד כִּ֚י הָרַ֣ג שָׁא֔וּל אֵ֖ת כֹּהֲנֵ֥י יְהוָֽה׃

And Abiathar told David that Saul had slain the LORD’S priests.

Read midrashic interpretation of I Samuel 22:21: and classical rabbinic exegesis.