Valmiki Ramayana Bala Kanda Sarga 24 Shloka 16

महातेजा: highly powerful, महामुनि: great sage, विश्वामित्र: Viswamitra, तम् addressing him, उवाच spoke, वत्स O Child, काकुत्स्थ Kakusthsa, एतत् दारुणं वनम् this dreadful forest, यस्य whose, श्रूयताम् let it be heard.

Viswamitra, the great sage radiating energy addressing Rama said, "O child of kakusthsa dynasty I shall tell you whose dreadful forest this is. Listen"