Bhagavad Gita 13.33
As space, though present everywhere, remains unaffected due to its subtlety, so too the Self, though present in all forms, retains its purity unalloyed.
यथा सर्वगतं सौक्ष्म्यादाकाशं नोपलिप्यते।सर्वत्रावस्थितो देहे तथाऽऽत्मा नोपलिप्यते॥yathā sarvagataṃ saukṣmyādākāśaṃ nopalipyate|sarvatrāvasthito dehe tathā''tmā nopalipyate||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).