Bhagwad Gita
Chapter 14, Verse 5
सत्त्वं रजस्तम इति गुणाः प्रकृतिसंभवाः।निबध्नन्ति महाबाहो देहे देहिनमव्ययम्।।14.5।।
Material nature consists of the three modes-goodness, passion and ignorance. When the living entity comes in contact with nature, he becomes conditioned by these modes.