Chapter 14 · The Three Qualities · Krishna said
Bhagavad Gita 14.10 — The gunas compete
रजस्तमश्चाभिभूय सत्त्वं भवति भारत। रजः सत्त्वं तमश्चैव तमः सत्त्वं रजस्तथा ॥
rajastamaścābhibhūya sattvaṃ bhavati bhārata | rajaḥ sattvaṃ tamaścaiva tamaḥ sattvaṃ rajastathā ||
Meaning
Sometimes sattva rises by overpowering rajas and tamas; sometimes rajas rises over sattva and tamas; and sometimes tamas rises over sattva and rajas.