Yoga Sūtra Chapter Four verse 14

परिणामैकत्वात् वस्तुतत्त्वम् ॥१४॥

pariṇāma-ekatvāt-vastu-tattvam ||14||

From the uniqueness of transformation,
the thatness of a substance.

pariṇāma - transformationekatvā - uniquenessvastu - substancetattva - principle; thatness