Valmiki Ramayana Aranya Kanda Sarga 47 Shloka 17
Original Shlokaदद्यान्न प्रतिगृह्णीयात्सत्यं ब्रूयान्न चानृतम्।।3.47.17।। एतद्ब्राह्मण रामस्य ध्रृवं व्रतमनुत्तमम्।
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दद्यात् giver, न प्रतिगृह्णीयात् not receive, सत्यम् truth, ब्रूयात् utter, अनृतम् other than truth, न च not utter, ब्राह्मण brahmin, एतत् this is, रामस्य Rama's, धृवम् resolve, अनुत्तमम् very great, व्रतम् vow.
O brahmin this is his firm resolve and his great vow: 'One should give and never take one should speak the truth and nothing but he truth.'