The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Verse 167

स होवाच यदूर्ध्वं गार्गि दिवो यदवा-क्पृथिव्या यदन्तरा द्यावापृथिवी इमे य-द्भूतं च भवच्च भविष्यच्चेत्याचक्षत आका-श एव तदोतं च प्रोतं चेति कस्मिन्नु ख-ल्वाकाश ओतश्च प्रोतश्चेति ॥ ७ ॥

In plain words

Yājñavalkya answered: Gārgī, everything you named — above the sky, beneath the earth, between earth and sky, past, present, future — all of it is woven together in space, and nowhere else. 'Then in what,' she asked at once, 'is space itself woven, through and through?'

Close to the Sanskrit

He said: Gārgī, that which is above heaven, that which is below the earth, that which is between these two, heaven and earth, and that which they used to call the past, the present, and the future — that, indeed, is woven, crosswise and lengthwise, in ether alone. But in what, then, is ether woven, crosswise and lengthwise?