Rasarnavasudhakara 3.493

3.493

tat padaṃ tanu-madhyāyā yenāśvattha-dalopamam |
tad-aśvattho' smi vṛkṣāṇām ity ūce bhagavān hariḥ ||

Because that private part of the slender-waisted woman resembles an Aśvattha leaf, / therefore the Lord Hari said, 'Among trees, I am the Aśvattha.'"

3.493.p1

iti |

3.493.p2

atra loka-prasiddhena aśvattha-daloru-mūlayoḥ sāmyena hetunā loka-prasiddhasyaiva bhagavad-aśvatthayor aikyasya sādhanaṃ hāsya-kāraṇam upapattiḥ |

Here, establishing the identity of the Lord and the Aśvattha tree—which is well known in the world—by the reason of the worldly resemblance between an Aśvattha leaf and the base of the thighs, is a cause for laughter, and constitutes logical justification (upapatti).