Valmiki Ramayana Bala Kanda Sarga 26 Shloka 6

अरिन्दम: destroyer of enemies, एवम् उक्त्वा having spoken thus, धनुर्मध्ये in the middle of the bow, मुष्टिम् the fist, बद्वा clinching, शब्देन with sounds, दिश: ten cardinal directions, नादयन् sounding, तीव्रम् severe, ज्याशब्दम् with twanging sounds of the bowstring, अकरोत् performed.

Rama, the destroyer of enemies having said so clinched the middle of the bow with his fist and filled the ten quarters with the resounding twanging of the bowstring.