Sayyiduna Iyad bin Himar (may Allah be pleased with him) narrates: I said, "O Messenger of Allah (peace and blessings be upon him)! A man from my tribe insults me, and he is of lesser status than me. Will I be sinful if I take revenge on him?" The Prophet (peace and blessings be upon him) said: "Two people who insult each other are both devils; both of them escalate the matter and speak falsely."
(Imam Ibn Hibban, may Allah have mercy on him, says:) The Prophet (peace and blessings be upon him) used the word 'devil' for the one who insults as a metaphor, because the devil guides that person towards this action until he escalates the matter and lies. This does not mean that both people who insult each other actually become devils.