Bṛhadāraṇyaka Upaniṣad ("Great Forest Teaching") 3.7.2

3.7.2

sa hovāca vāyurvaigautama tatsūtraṃ vāyunā vai gautama sūtreṇāyaṃ ca lokaḥ paraśca lokaḥ sarvāṇi ca bhūtāni saṃdṛbdhāni bhavanti tasmādvai gautama puruṣaṃ pretamāhurvyasram̐ siṣatāsyāṅgānīti vāyunā hi gautama sūtreṇa saṃdṛbdhāni bhavantītyevamevaitadyājñavalkyāntaryāmiṇaṃ brūhīti

Yâgñavalkya said: 'Vâyu (air) is that thread, O Gautama. By air, as by a thread, O Gautama, this world and the other world, and all creatures are strung together. Therefore, O Gautama, people say of a dead person that his limbs have become unstrung; for by air, as by a thread, O Gautama, they were strung together.'
The other said: 'So it is, O Yâgñavalkya. Tell now (who is) the puller within.'