Bhagavad Gita 4.30

अपरे नियताहारः प्राणान्प्राणेषु जुह्वति |
सर्वेऽपयेते यज्ञविदो यज्ञक्षपिटकल्मषा:

Translation

Yet others curtail their food intake and offer the breath into the life-energy as sacrifice. All these knowers of sacrifice are cleansed of their impurities as a result of such performances.