John Gill Commentary 1 Samuel 22:21

"And Abiathar told David that Saul had slain Jehovah`s priests." — 1 Samuel 22:21 (ASV)

And Abiathar showed David that Saul had slain the Lord's
priests .
Of which perhaps he had not as yet heard; though tidings of such a nature generally fly swiftly; and a sorrowful shocking account he had to give, and which was so to David.