CC Madhya 19.141
śatadhā kalpitasya ca
bhāgo jīvaḥ sa vijñeya
iti cāha parā śrutiḥ
bāla-agra — the tip of a hair; śata-bhāgasya — of one hundredth; śatadhā — into one hundred parts; kalpitasya — divided; ca — and; bhāgaḥ — minute portion; jīvaḥ — the living entity; saḥ — that; vijñeyaḥ — to be understood; iti — thus; ca — and; āha — have said; parā — chief; śrutiḥ — Vedic mantras.
“ ‘If we divide the tip of a hair into one hundred parts and then take one part and divide this into another one hundred parts, that ten-thousandth part is the dimension of the living entity. This is the verdict of the chief Vedic mantras.’
The first three padas of this verse from the Pañcadaśī-citra-dīpa (81) are taken from the Śvetāśvatara Upaniṣad (5.9).