Mahabharata Shalya Parva Chapter 61:4

Mahabharata Shalya Parva (Gada Yuddha Parva) Chapter 61:4 If I had not adopted such deceitful ways in battle, victory would never have been yours, nor kingdom, nor wealth! Those four were very high-souled warriors and regarded as Atirathas in the world. The very Regents of the Earth could not slay them in fair fight! Similarly, the son of Dhritarashtra, though fatigued when armed with the mace, could not be slain in fair fight by Yama himself armed with his bludgeon! You should not take it to heart that this foe of yours hath been slain deceitfully. When the number of one's foes becomes great, then destruction should be effected by contrivances and means. The gods themselves, in slaying the Asuras, have trod the same way. That way, therefore, that hath been trod by the gods, may be trod by all. We have been crowned with success. It is evening. We had better depart to our tents. Let us all, ye kings, take rest with our steeds and elephants and cars." Hearing these words of Vasudeva, the Pandavas and the Pancalas, filled with delight, roared like a multitude of lions. All of them blew their conchs and Jadava himself blew Panchajanya, filled with joy, O bull among men, at the sight of Duryodhana struck down in battle.'"