Bhagavatapurana 3.6.31

3.6.31

bāhubhyo 'vartata kṣatraṃ kṣatriyas tad anuvrataḥ /
yo jātas trāyate varṇān pauruṣaḥ kaṇṭaka-kṣatāt //

31. From His arms was born the Power of protection, as also the Kshatriya who is devoted to that duty; for the Kshatriya born as the Amsa of the Purusha protects the Varnas from the affliction caused by thieves and others (lit. who are the thorn in the side of the world).