Shiva Purana
॥ व्यास उवाच ॥ ब्राह्मणत्वं हि दुष्प्राप्यं निसर्गाद्ब्राह्मणो भवेत् ॥ ईश्वरस्य मुखात्क्षत्रं बाहुभ्यामूरुतो विशः ॥ १ ॥
Vyasa said:- Being a Brahmin is difficult to attain and one should be a Brahmin by nature. From the mouth of the lord enter the kṣatriyas with your arms and thighs
english translation
॥ vyAsa uvAca ॥ brAhmaNatvaM hi duSprApyaM nisargAdbrAhmaNo bhavet ॥ Izvarasya mukhAtkSatraM bAhubhyAmUruto vizaH ॥ 1 ॥
hk transliteration by Sanscript