Albert Barnes Commentary 2 Samuel 15:27

"The king said also unto Zadok the priest, Art thou [not] a seer? return into the city in peace, and your two sons with you, Ahimaaz thy son, and Jonathan the son of Abiathar." — 2 Samuel 15:27 (ASV)

Are you not a seer? - If the text is correct, the meaning would be, “Are you not a seer? Therefore go back to the city, observe, and inform me of what you see” (2 Samuel 15:28). Others, by a slight alteration of the original text, read, “Are you not a chief” (priest), etc.