Hassan bin Fa'id narrates from Sayyiduna Umar (may Allah be pleased with him) that bravery and cowardice are in people's nature: you will find a man fighting on behalf of someone he does not even know, and you will find a man fleeing from his own father. Nobility of lineage (hasab) means wealth, and honour (karam) means piety; being better than any Persian or non-Arab can only be on the basis of piety.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18562