Valmiki Ramayana Sundara Kanda Sarga 49 Shloka 18

अयम् this, अधर्मः unrighteousness, बलवान् powerful, न स्याद्यदि if it was not, अयम् this, राक्षसेश्वरः lord of demons, सशक्रस्य including Indra, सुरलोकस्यापि even of the world of gods, रक्षिता lord, स्यात् would become.

'If only this lord of demons was not unrighteous, he could have become even the lord (protector) of gods including Indra.