योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-83, verse-20

तत्कल्पान्तमहाशून्ये एतस्मिन्परमाम्बरे ।
कथं चिन्नाम वाऽचेत्यं चेता चेतति चिद्धनः ॥ २० ॥

tatkalpāntamahāśūnye etasminparamāmbare ,
kathaṃ cinnāma vā'cetyaṃ cetā cetati ciddhanaḥ 20

20. How then does it happen at the end of the kalpa, when everything is lost in the formless void of vacuity, that this consolidated form of intellect, known as Siva remains and thinks in itself.