Mbh 8.32.3a

"'Shalya said "Thou insultest me, O son of Gandhari, or without doubt suspectest me, since thou solicitest me, without hesitation, saying, 'Act thou as a driver.' Regarding Karna to be superior to ourselves, thou applaudest him thus. I, however, do not regard the son of Radha as my equal in battle. Assign to me a much greater share, O lord of Earth. Destroying that in battle, I will return to the place I come from. Or, if thou wishest, I will, O delighter of the Kurus, contend, single-handed, with the enemy. While engaged in consuming the foe, behold thou my prowess today. Brooding upon an insult, O thou of Kuru's race, a person like ourselves never engageth in my task. Do not have thy doubts about me. Never shouldst thou humiliate me in battle. Behold these two massive arms of mine, strong as the thunder. Behold also my excellent bow, and these shafts that resemble snakes of virulent poison. Behold my car, unto which are yoked excellent steeds endued with the speed of the wind. Behold also, O son of Gandhari, my mace decked with gold and twined with hempen chords. Filled with wrath, I can split the very Earth, scatter the mountains, and dry up the oceans, with my own energy, O king. Knowing me, O monarch, to be so capable, of afflicting the foe, why dost thou appoint me to the office of driver in battle for such a low-born person as Adhiratha's son? It behoveth thee not, O king of kings, to set me to such mean tasks! Being so superior, I cannot make up my mind to obey the commands of a sinful person. He that causeth a superior person arrived of his own will and obedient from love, to yield to a sinful wight, certainly incurreth the sin of confusing the superior with the inferior. Brahman created the Brahmanas from his mouth, and the Kshatriyas from his arms. He created the Vaishyas from his thighs and the Shudras from his feet. In consequence of the intermixture of those four orders, O Bharata, from those four have sprung particular classes, viz.