Valmiki Ramayana Ayodhya Kanda Sarga 63 Shloka 11

कौशल्ये O Kausalya, शब्दवेधी one who can shoot arrows aiming at the target by sound, कुमारः इति in chidhood itself, लब्धशब्देन attaining knowledge of sound, कुमारेण in my youth, धनुष्मता as an archer, मया by me, इदम् this, पापम् sin, कृतम् was done.

O Kausalya in my youth I was a great archer who could hit the target by its sound. As such I committed this sin.