Bhagavad Gita · 13.33

यथा सर्वगतं सौक्ष्म्यादाकाशं नोपलिप्यते।सर्वत्रावस्थितो देहे तथात्मा नोपलिप्यते॥

yathā sarva-gataṁ saukṣhmyād ākāśhaṁ nopalipyate sarvatrāvasthito dehe tathātmā nopalipyate

As the all-pervading space, being subtle, is not tainted by anything, so the Self seated everywhere in the body is not tainted.

— Bhagavad Gita 13.33

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)