Valmiki Ramayana Kishkindha Kanda Sarga 1 Shloka 56
Original Shlokaशृणु लक्ष्मण सन्नादं वने मद्विवर्धनम्। पुष्पिताग्रेषु वृक्षेषु द्विजानामुपकूजताम्।।4.1.56।।
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लक्ष्मण Lakshmana, वने in the forest, पुष्पिताग्रेषु वृक्षेषु on the blossoming tree tops, उपकूजताम् of warbling ones, द्विजानाम् of birds, मद्विवर्धनम् that which increases love, शृणु listen
'Losten, O Lakshmana to the sweet warblings of the birds on the blossoming treetops of the forest. My love for her (Sita) enhances with their sweet voices.