Valmiki Ramayana Aranya Kanda Sarga 10 Shloka 18
Original Shlokaसंश्रुत्य च न शक्ष्यामि जीवमानः प्रतिश्रवम्। मुनीनामन्यथा कर्तुं सत्यमिष्टं हि मे सदा।।3.10.18।।
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संश्रुत्य having promised, जीवमानः as long as there is life in me, मुनीनाम् of sages, प्रतिश्रवम् promise, अन्यथा otherwise, कर्तुम् to do, न shall not do, शक्ष्यामि I will not be able, सदा always, मे to me, सत्यम् truth, इष्टं हि is dear.
Having promised the sages, I cannot do otherwise as long as I have life in me. To me truth is always dear.