Bhagavad Gita Chapter 13.21
karya-kara?a-kart?tve
hetu? prak?tir ucyate
puru?a? sukha-du?khana?
bhokt?tve hetur ucyate
Translation
Nature is said to be the cause of all material causes and effects, whereas the living entity is the cause of the various sufferings and enjoyments in this world.