Mahabharata Bhishma Parva Chapter 120:6

Mahabharata Bhishma Parva (Bhagavat-Gita Parva) Chapter 120:6 Beholding that high-souled son of Ganga, that chief of the Bharatas, they walked round him, and the Sun being then in the southern solstice, they said, addressing one another, these words, 'Being a high-souled person, why should Bhishma pass out (of the world) during the southern declension?' Having said these words, those swans went away, proceeding towards the southern direction. Endued with great intelligence, Bhishma, O Bharata. beholding them, reflected for a moment. And the son of Santanu then said unto them, 'I will never pass out (of the world) as long as the Sun is in the southern solstice. Even this is my resolve. I will proceed to my own ancient abode when the Sun reacheth the northern solstice. Ye swans, I tell you this truly. Expectant of the northern declension I will hold my life. Since I have the fullest control over the yielding up of my life, I will, therefore, hold life, expectant of death during the northern declension. The boon that was granted to me by my illustrious sire, to the effect that my death would depend on my own wish. O, let that boon become true. I will hold my life, since I have control in the matter of laying it down.' Having said these words to those swans, he continued to lie down on his bed of arrows. When that crest of the Kuru race, viz., Bhishma of great energy, fell down, the Pandavas and the Srinjayas uttered leonine shouts. When the grandsire of the Bharatas who was endued with great might was overthrown, thy son, O bull of Bharata's race, knew not what to do. And all the Kurus were entirely deprived of their senses. And the Kurus headed by Kripa, and Duryodhana, sighed and wept. And from grief they remained for a long while deprived of their senses. And they remained perfectly still, O monarch, without setting their hearts on battle. As if seized by thighs, they stood motionless, without proceeding against the Pandavas. When Santanu's son Bhishma of mighty energy, who was (regarded as) unslayable, was slain, all of us thought that the destruction of the Kuru king was at hand. Vanquished by Savyasachin, with our foremost heroes slain, and ourselves mangled with sharp arrows, we knew not what to do. And the heroic Pandavas possessed of massive arms that looked like spiked maces, having obtained the victory and won a highly blessed state in the other world, all blew their great conches. And the Somakas and the Panchalas all rejoiced, O king. Then when thousands of trumpets were blown, the mighty Bhimasena slapped his arm-pits and uttered loud shouts. When the all-powerful son of Ganga was slain, the heroic warriors of both armies, laying down their weapons, began to reflect thoughtfully. And some uttered loud shrieks and some fled away, and some were deprived of their senses. And some censured the practices of the Kshatriya order and some applauded Bhishma. And the Rishis and the Pitris all applauded Bhishma of high vows. And the deceased ancestors of the Bharatas also praised Bhishma. Meanwhile the valiant and intelligent Bhishma, the son of Santanu, having recourse to that Yoga which is taught in the great Upanishads and engaged in mental prayers, remained quiet, expectant of his hour.