Valmiki Ramayana Sundara Kanda Sarga 45 Shloka 9

आशुचरः moving fast, सः कपिः that monkey, विमले in the clear, अम्बरे sky, विचरन् moving, तेषां वीराणाम् of the heroes, शरान् by the arrows, रथवेगं च and the speed of their chariot, मोघयामास rendered futile.

Then the monkey moving fast in the clear sky rendered the arrows of the giant heroes and speeding chariots futile.