yathā mahānti bhūtāni
bhūteṣūccāvaceṣv anu
praviṣṭāny apraviṣṭāni
tathā teṣu na teṣv aham
yathā - as; mahānti - the universal; bhūtāni - elements; bhūteṣu - in the living entities; ucca-avaceṣu - both gigantic and minute; anu - after; praviṣṭāni - situated internally; apraviṣṭāni - situated externally; tathā - so; teṣu - in them; na - not; teṣu - in them; aham - I.
This is a quotation from Śrīmad-Bhāgavatam (2.9.35). It is also the third verse of the catuḥ-ślokī. For an explanation see Ādi-līlā, chapter one, text 55.