Valmiki Ramayana Ayodhya Kanda Sarga 74 Shloka 18
Original Shlokaइन्द्रोऽप्यश्रुनिपातं तं स्वगात्रे पुण्यगन्धिनम्। सुरभिं मन्यते दृष्ट्वा भूयसीं तां सुरेश्वरः।।2.74.18।।
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सुरेश्वरः lord of the gods, इन्द्रोऽपि Indra, स्वगात्रे on his body, पुण्यगन्धिनम् of holy fragrance, तम् that, अश्रुपातम् flow of tears, दृष्ट्वा on seeing, ताम् her, भूयसीम् venerated, सुरभिम् as Kamadhenu, मन्यते thought
When Indra, lord of the gods, saw those tears of holy fragrance fallen on his body he understood that the tears were shed by the venerated Kamadhenu.