The Mahabharata - pg. 165

The moral of this striking story of Dharmavyadha so skilfully woven by Vedavyasa into the Mahabharata, is the same as the teaching of Gita, that man reaches perfection by the honest pursuit of whatever calling falls to his lot in life, and that this is really worship of God Who created and pervades all. The occupation may be one he is born to in society or it may have been forced on him by circumstances or he may have taken it up by choice but what really matters is the spirit of sincerity and faithfulness with which he does his life's work. Vedavyasa emphasises this great truth by making a scholarly brahmana, who did not know it, learn it from a butcher, who lived it in his humble and despised life.