Chapter 12 · The Yoga of Devotion · Krishna said
Bhagavad Gita 12.3 — Worship of the formless
ये त्वक्षरमनिर्देश्यमव्यक्तं पर्युपासते। सर्वत्रगमचिन्त्यञ्च कूटस्थमचलन्ध्रुवम् ॥
ye tvakṣaramanirdeśyamavyaktaṃ paryupāsate | sarvatragamacintyañca kūṭasthamacalandhruvam ||
Meaning
Those who worship the imperishable — beyond words, unseen, everywhere, beyond thought, unchanging, unmoving and eternal —