🕉 Svetasvatara Upanishad - Chapter 5

 Of the size of a thumb, but brilliant, like the sun, the jiva possesses both volition and

egoism. It is endowed with the qualities of both buddhi and Atman.

Therefore it is seen as another entity (as different from Brahman) and as small as the point of a needle.

Mantra 8. The One Immanent God