Valmiki Ramayana Kishkindha Kanda Sarga 11 Shloka 69
Original Shlokaतथा ब्रुवाणं सुग्रीवं प्रहसन् लक्ष्मणोऽब्रवीत्। कस्मिन्कर्मणि निर्वृत्ते श्रद्दध्या वालिनो वधम्4.11.69।।
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लक्ष्मणः Lakshmana, तथा that way, ब्रुवाणम् while he spoke, सुग्रीवम् to Sugriva, प्रहसन् with a smile, अब्रवीत् said, कस्मिन् in which, कर्मणि in action, निवृत्ते when carried out, वालिनः Vali's, वधम् killing, श्रद्दध्याः trust
Smiling, Lakshmana asked Sugriva, 'By what action will you trust?. By the fulfilment of which task (by Rama) will you have faith?'