Valmiki Ramayana Yuddha Kanda Sarga 67 Shloka 74
Original Shlokaएवंगृहीतेसुग्रीवेकिंकर्तव्यंमयाभवेत् ।।6.67.74।। यद्वैन्यायंमयाकर्तुंतत्करिष्यामिसर्वधा । भूत्वापर्वतसङ्काशोनाशयिष्यामिराक्षसम् ।।6.67.75।।
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सुग्रीवे Sugriva, एवम् in this way, गृहीते captured, मया my, किम् what, कर्तव्यम् duty, भवेत् will be, मया my, यत् that which, कर्तुम् will do, न्याय्यम् justice, तत् that, सर्वधा thought, करिष्यामि will do, पर्वतसङ्काशः one who is like a mountain, भूत्वा to be done, राक्षसम् Rakshasa, नाशयिष्यामि will destroy.
'Sugriva has been caught. What is my duty now? I will do what is just. I will destroy that Rakshasa who is in the form of a mountain', thought Maruti.