SB 1.9 - Bhīṣma - an eternal associate of Kṛṣṇa

Thereafter, both men and demigods sounded drums in honor, and the honest royal order commenced demonstrations of honor and respect. And from the sky fell showers of flowers. The living beings on earth and on the Bhūr and Bhuvar planets, and the demigods from the Svar planets all knew Bhīṣma as a great warrior and devotee. They all paid respects to him by showering flowers. This showering of flowers is a sign of recognition by great demigods and should not be compared to the decoration of a dead body. Bhīṣma’s body had become completely spiritual due to his being a great devotee of the Lord. Special ceremonies are observed for such spiritual bodies, and should never be imitated to honor a material person however great he may be by observing a so-called jayanti ceremony.

After performing funeral rituals for the dead body of Bhīṣmadeva, Yudhiṣṭhira was momentarily overtaken with grief. Bhīṣma was a well wisher, grand father, friend and philosopher to Yudhiṣṭhira even up to the last moment of his life. Thus the king did the funeral rites, although Bhīṣma was a liberated soul and so did not need the customary rites to be performed. Though Bhīṣma is an eternal associate of the Lord, his aṁśa had entered into Vasu, who then descended from the heavenly planets to earth. Thus Bhīṣma is shown by the Lord to give up his body. His aṁśa who was situated in Vasu gave up his body and Bhīṣma himself attained the spiritual world. The Vedānta (3.3.33) says that those designated by the Lord remain in their posts on earth as long as the Lord chooses. It has been said that Bhīṣma, an eternal associate of the Lord, attained Kṛṣṇa as the charioteer in aprakaṭa-līlā. Thus when it is said that Bhīṣma stopped breathing and gave up his body, it means he simply became detached from his manifested body on earth. Yudhiṣṭhira was sad for a short period to follow the custom of the people since he understood that Bhīṣma did not have a material body.