Valmiki Ramayana Yuddha Kanda Sarga 111 Shloka 5
Original Shlokaब्रह्मणानिर्मितंपूर्वमिन्द्रार्थममितौजसा । दत्तंसुरपतेःपूर्वंत्रिलोकजयकाङ्क्षिणः ।।6.111.5।।
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पूर्वम् earlier, इन्द्रार्थम् for Indra's sake, अमितेजसा very powerful, ब्रह्मणा by Brahma, निर्मितम् for the sake, पूर्वम् earlier, त्रिलोकजयकाङ्क्षिणः desirous to gain the three worlds, सुरपतेः king of gods, दत्तम् bestowed
Earlier, this powerful arrow was created for Indra's sake by Brahma and was bestowed to Indra, the king of gods, who was desirous of conquering the three worlds.