It is narrated from Sayyiduna Samurah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Soon Allah will fill your hands with non-Arabs, then He will make them lions who do not flee, and they will kill your fighters and consume your fay' (spoils)."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6891