Mahabharata, Book 5, Section CXCVIउद्योगपर्व

“Sanjaya said, ‘When the night passed away and morning came, thy sons once more, in the midst of all the troops, asked their grandsire, saying, “O son of Ganga, this army that is ready for fight, of Pandu’s son, that abounds with men, elephants, and steeds, that is crowded with Maharathas, that is protected by these mighty bowmen endued with great strength, viz., Bhima and Arjuna and others headed by Dhrishtadyumna and all resembling the very regents of the world, that is invincible and incapable of being withstood, that resembles the unbounded sea,—this sea of warriors incapable of being agitated by the very gods in battle, in how many days, O son of Ganga, O thou of great effulgence, canst thou annihilate it, and in what time can that mighty bowman, our preceptor (Drona), in what time also the mighty Kripa, in what time Karna who taketh a pleasure in battle, and in what time that best of Brahmanas, viz., the son of Drona, can each annihilate it? Ye that are in my army are all acquainted with celestial weapons! I desire to know this, for the curiosity I feel in my heart is great! O thou of mighty arms, it behoveth thee to say this to me!"

“‘Bhishma said, “O foremost one of the Kurus, O lord of the earth, thou enquirest about the strength and weakness of the foe. This, indeed, is worthy of thee. Listen, O king, as I tell thee the utmost limit of my power in battle, or of the energy of my weapons, or of the might of my arms, O thou of mighty arms! As regards ordinary combatants, one should fight with them artlessly. As regards those that are possessed of powers of deception, one should fight with them aided by the ways of deception. Even this is what hath been laid down in respect of the duties of warriors. I can annihilate the Pandava army, O blessed monarch, taking every morning ten thousand (ordinary) warriors and one thousand car-warriors as my share from day to day. Cased in mail and always exerting myself actively, I can, O Bharata, annihilate this large force, according to this arrangement as regards both number and time. If, however, stationed in battle, I shoot my great weapons that slay hundreds and thousands at a time, then I can, O Bharata, finish the slaughter in a month.”’

“Sanjaya continued, ‘Hearing these words of Bhishma, king Duryodhana then asked Drona, O monarch, that foremost one of Angira’s race, saying, “O preceptor, in what time canst thou annihilate the troops of Pandu’s son?” Thus addressed by him, Drona said smilingly, “I am old, O mighty-armed one! My energy and activity have both become weak. With the fire of my weapons I can consume the army of the Pandavas, like Santanu’s son Bhishma, I think, in a month’s time. Even this is the limit of my power, even this is the limit of my strength.” Then Saradwat’s son Kripa said that he could annihilate the foe in two month’s time. Drona’s son (Aswatthaman) pledged himself to annihilate the Pandava army in ten nights. Karna, however, acquainted as he was with weapons of high efficacy, pledged himself to achieve that feat in five days. Hearing the words of the Suta’s son the son of the ocean-going (Ganga) laughed aloud and said, “As long, O son of Radha, as thou encounterest not in battle Partha with his arrows, conch, and bows and rushing to the combat on his car with Vasudeva in his company, so long mayest thou think so! Why, thou art capable of saying anything, even what thou pleasest!”’"