The Prophet (sallallaahu alayhi wa sallam) said:
“Whosoever fights under the banner of ignorance, or is angered for the sake of al-Asabiyyah (tribalism, nationalism) or calls to al-Asabiyyah, and he dies, then he has died a death of al-Jaahiliyyah.”
Graded Saheeh by al-Albaanee in Silsilah al-Saheehah (1/720)