Aeneid 6.417-25 (c.19 BC)
The Sibyl drugs Cerberus in his lair to allow Aeneas to enter the underworld.
Cerberus haec ingens latratu regna trifauci
personat, adverso recubans immanis in antro.
Cui vates, horrere videns iam colla colubris,
melle soporatam et medicatis frugibus offam
obicit. Ille fame rabida tria guttura pandens
corripit obiectam, atque immania terga resolvit
fusus humi, totoque ingens extenditur antro.
Occupat Aeneas aditum custode sepulto,
evaditque celer ripam inremeabilis undae.