Valmiki Ramayana Kishkindha Kanda Sarga 24 Shloka 10
Original Shlokaवधो हि मे मतो नासीत्स्वमाहात्म्याव्यतिक्रमात्। ममाऽसीद्बुद्धिदौरात्म्यात्प्राणहारी व्यतिक्रमः4.24.10।।
1 source checked for this shloka
स्वमाहात्म्याव्यतिक्रमात् transgress one's own noble nature, मे वधः killing, मतः acceptable, नासीत् was not, मम me, बुद्धिदौरात्म्यात् due to my wicked thought, प्राणहारी slayer, व्यतिक्रमः overlooking आसीत् became.
'The idea of killing me was not acceptable to his noble nature, while my wicked thought caused his death.