Valmiki Ramayana Bala Kanda Sarga 65 Shloka 24
Original Shlokaतत: प्रसादितो देवैर्वसिष्ठो जपतां वर:।।1.65.24।। सख्यं चकार ब्रह्मर्षिरेवमस्त्विति चाब्रवीत्।
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तत: there upon, देवै: by devatas, प्रसादित: propitiated, जपतां वर: the best among ascetics, वसिष्ठ: Vasishta, सख्यम् friendship, चकार made, एवम् thus, ब्रह्मर्षि: अस्तु become brahmarshi, इति in this manner saying so, अब्रवीत् च spoken.
Thereupon, pleased by the gods, Vasishta, the best among ascetics, lovingly said to Viswamitra "You are a Brahmarshi, let it be so".