Srimad Bhagavatam Canto 08, Chapter 01, Text 17

SB 8.1.17

sri-suka uvaca
iti mantropanisadam
 vyaharantam samahitam
drstvasura yatudhana
 jagdhum abhyadravan ksudha
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Sukadeva Gosvami continued: Svayambhuva Manu was thus in a trance, chanting the mantras of Vedic instruction known as the Upanisads. Upon seeing him, the Raksasas and asuras, being very hungry, wanted to devour him. Therefore they ran after him with great speed.
Srimad Bhagavatam Canto 08, Chapter 01, Text 16
Srimad Bhagavatam Canto 08, Chapter 01, Text 18