Valmiki Ramayana Yuddha Kanda Sarga 103 Shloka 38

रक्षसा Rakshasa, दशग्रीवेण with ten necks, रणमूर्धनि in the forefront of battle, निरस्यमानःnot had opportunity, रामः for Rama, सायकान् weapons, अभिसन्धातुम् even to fix, नाशक्नोत् not feasible

While Ravana with ten heads and arms was ready in the forefront of the battle, Sri Rama had no possibility to fix his arrows.