Valmiki Ramayana Ayodhya Kanda Sarga 105 Shloka 44
Original Shlokaधार्मिकेणानृशंसेन नरेण गुरुवर्तिना। भवितव्यं नरव्याघ्र परलोकं जिगीषता।।2.105.44।।
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नरव्याघ्र O best of men, परलोकम् the next world, जिगीषता by one who aspires to conquer, नरेण by a man, धार्मिकेण by being virtuous, नृशंसेन compassionate, गुरुवर्तिना obedient to preceptors, भवितव्यम् shall happen.
O best of men, if a man aspires to conquer the higher world, he should remain virtuous, compassionate and obedient to his preceptors.