Valmiki Ramayana Ayodhya Kanda Sarga 64 Shloka 59

देवि O Devi (Kausalya), तदा then, शब्दवेध्यनुशिक्षिणा trained in discharging the arrow in the direction of sound, मया by me, बाल्यात् out of ignorance, स्वयम् myself, कृतम् committed, तत् such, एतत् this, पापम् sin, चिन्तयानेन reflecting, स्मृतम् recollected.

While reflecting about it now, O Devi (Kausalya) I recollect this sin committed by me unintentionally, with childish pranks while practising the art of hitting a target by its sound.