Sūta Gosvāmī said: Thus Bhīṣmadeva merged himself in the Supersoul, Lord Śrī Kṛṣṇa, the Supreme Personality of Godhead, with his mind, speech, sight and actions, and thus he became silent, and his breathing stopped.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सूत उवाच । कृष्ण एवं भगवति मनोवाग्दृष्टिवृत्तिभिः । आत्मन्यात्मानमावेश्य सोऽन्तःश्वास उपारमत्
sūta uvāca | kṛṣṇa evaṃ bhagavati manovāgdṛṣṭivṛttibhiḥ | ātmanyātmānamāveśya so'ntaḥśvāsa upāramat
SB 1.9.43