Valmiki Ramayana Kishkindha Kanda Sarga 38 Shloka 26
Original Shlokaतव देव प्रसादाच्च भ्रातुश्च जयतां वर। कृतं न प्रतिकुर्याद्यः पुरुषाणां स दूषकः।।4.38.26।।
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देव O lord, जयतां वर best of the victorious men, तव your, भ्रातुश्च your brother's, प्रसादात् by the grace, च also, कृतम् accomplished, यः whoever, न प्रतिकुर्यात् not help in return, पुरुषाणाम् among men, स दूषकः the lowest.
'O victorious lord he who does not repay the help got through your grace and your brother's is despicable among men.