Mbh 6.116.2a

Sanjaya said, “I will presently describe to thee, O Bharata, how the Kauravas fought with the Pandavas, and how that battle took place. Day after day many mighty car-warriors of thy army, excited with wrath, were despatched to the other world by the diadem-decked (Arjuna) with his great weapons. The ever-victorious Kuru warrior Bhishma also, agreeably to his vow, always caused a great carnage among the Partha army. O chastiser of foes, beholding Bhishma, fighting at the head of the Kurus, and Arjuna also fighting at the head of the Panchalas, we could not say truly on which side the victory would declare itself. On the tenth day of battle, when Bhishma and Arjuna encountered each other, awful was the carnage that took place. On that day, O scorcher of foes, Santanu’s son, Bhishma, conversant with high and mighty weapons, repeatedly slew thousands upon thousands of warriors. Many, O Bharata, whose names and families were not known, but who, endued with great bravery, were unretreating from battle, were on that day slain by Bhishma. Scorching the Pandava army for ten days, Bhishma of virtuous soul, gave up all desire of protecting his life. Wishing his own slaughter presently at the head of his troops,--‘No more shall I slay large numbers of foremost of warriors.’--thought thy mighty-armed sire Devavrata. And seeing Yudhishthira near him, O king, he addressed him, saying, ‘O Yudhishthira, O thou of great wisdom, O thou that art acquainted with every branch of learning, listen to these righteous and heaven-leading words, O sire, that I say. O Bharata, I no longer desire to protect, O sire, this body of mine. I have passed much time in slaying large numbers of men in battle. If thou wishest to do what is agreeable to me, strive to slay me, placing Partha with the Panchalas and the Srinjayas at thy van’. Ascertaining this to be his intention, king Yudhishthira of true sight proceeded to battle with the Srinjayas (for his support).