Valmiki Ramayana Kishkindha Kanda Sarga 30 Shloka 72
Original Shlokaशुभं वा यदि वा पापं यो हि वाक्यमुदीरितम्। सत्येन प्रतिगृह्णाति स वीरः पुरुषोत्तमः4.30.72।।
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यः हि he who, शुभं वा good or, यदि वा or else, पापम् sin, उदीरितम् which has been promised, वाक्यम् words, सत्येन truly, प्रतिगृह्णाति will follow, सः वीरः he is a hero, पुरुषोत्तमः the best of men.
'(On the other hand) he who honours his promise, whether good or bad, is truly heroic, the best of men.'