Valmiki Ramayana Kishkindha Kanda Sarga 2 Shloka 3
Original Shlokaनैव चक्रे मनः स्थातुं वीक्षमाणो महाबलौ। कपेः परमभीतस्य चित्तं व्यवससाद ह4.2.3।।
1 source checked for this shloka
महाबलौ very strong persons, वीक्षमाणः beholding, स्थातुम् to be steady, मनः to his mind, नैव चक्रे did not, परमभीतस्य much frightened, कपेः monkey's, चित्तम् mind, व्यवससाद ह sunk
Beholding the two strong heroes, the monkey (Sugriva) was very much frightened. His heart sank.