Shatapatha Brahmana 10.1.1.8

10.1.1.8

aṅguṣṭhā iti pumāṃsaḥ aṅgulaya iti striyaḥ karṇāviti pumāṃsau bhruvāviti striyā oṣṭhāviti pumāṃsau nāsike iti striyau dantā iti pumāṃso jihveti strī sarva eva mithunaḥ so'nena mithunenātmanaitam mithunamagnimapyeti

The thumbs (and great toes, 'aṅgushtha,' m.) are males, and the fingers and toes ('aṅguli,' f.) females; the ears ('karna' m.) are males, and the eyebrows ('bhrû,' f.) females; the lips ('oshtha,' m.) are males, and the nostrils ('nâsikâ,' f.) females; the teeth ('danta,' m.) are males, and the tongue ('gihvâ,' f.) is a female: indeed the whole (body) consists of pairs, and with this body, consisting of pairs, that (vital fluid) enters this Agni (the fire-altar), consisting of pairs.