Mahabharata Aswamedha Parva Chapter 84:2

Mahabharata Aswamedha Parva (Anugita Parva) Chapter 84:2 That Arjuna voluntarily spared their king was well understood by them. The prince of the Gandharas then began to fly away from the field, accompanied by all his warriors who resembled a flock of frightened deer. The Gandharas, through fear, lost their senses and wandered over the field, unable to escape. Arjuna, with his broad-headed shafts, cut off the heads of many. Many there were who lost their arms in consequence of Arjuna's arrows, but so stupefied were they with fear that they were not aware of the loss of that limb. Verily, the Gandhara army was exceedingly afflicted with those large shafts which Partha sped from Gandiva. That army, which then consisted of frightened men and elephants and horses, which lost many warriors and animals, and which had been reduced to a rabble and put to rout, began to wander and wheel about the field repeatedly. Among those foes who were thus being slaughtered none could be seen standing in front of the Kuru hero famed for foremost of feats. No one could be seen who was able to bear the prowess of Dhananjaya. Then the mother of the ruler of the Gandharas, filled with fear, and with all the aged ministers of state, came out of her city, bearing an excellent Arghya for Arjuna. She forbade her brave son of steady heart from fighting any longer, and gratified Jishnu who was never fatigued with toil. The puissant Vibhatsu worshipped her and became inclined to show kindness towards the Gandharas. Comforting the son of Sakuni, he said, "Thou hast not, O mighty-armed hero, done what is agreeable to me by setting thy heart upon these measures of hostility. O slayer of heroes, thou art my brother, O sinless one. Recollecting my mother Gandhari, and for the sake of Dhritarashtra also, I have not taken thy life. It is for this, O king, that thou livest still. Many of thy followers, however, have been slain by me. Let not such a thing happen again. Let hostilities cease. Let not thy understanding again go astray. Thou shouldst go to the Horse-sacrifice of our king which comes off on the day of full moon of the month of Chaitra.