Valmiki Ramayana Ayodhya Kanda Sarga 42 Shloka 11

धर्मात्मा virtuous one, तापसम् wearing the robes of an ascetic, पुत्रम् son, सञ्चिन्त्य remembering, कामात् intentionally, ब्राह्मणम् to a brahmin, हत्वेव as if slew, पाणिना with hand, अग्निम् to fire, स्पृष्ट्वा इव as if touched, अन्वतप्यत plunged in grief.

That virtuous Dasaratha, recalling (the sight of) his son with the robes of an ascetic, burned with remorse as if he had intentionally slain a brahmin or placed his hand in fire.