Valmiki Ramayana Aranya Kanda Sarga 3 Shloka 21

तदा then, तौ both, उद्यतौ coming on, कृष्णसर्पोपमौ both looking like black serpents, शुभौ auspicious, ख़ड्गौ the two swords, क्षिप्रम् quickly, उद्यम्य raising, तूर्णम् at once, तस्य at him, आपेततुः fell upon, बलात् strongly, प्रहरताम् struck तस्य him.

Then both Rama and Lakshmana quickly raised their swords which looked like black serpents and at once fell upon the demon who was going to strike with great force.