Rashi: It is an earthenware Kli in which wine is put.

Radak: It is a parable for two matters. (a) One fills it with wine, and it absorbs in its walls. So they will be full of intoxication; this is a metaphor for many afflictions. Just like a drunkard has no Da'as and does not know what to do, so one who is bombarded with afflictions is confounded and startled and does not know what to do. (b) When one strikes a Nevel on a Nevel, its shards shatter. Nifutz is written regarding Nevalim - "v'Nivleihem Yenapetzu" (48:12). So there will be quarrels among them about their many afflictions, even fathers with their sons, and brothers, will smash each other. They will be destroyed via the enemy, and via themselves!

Malbim: Why must you say so in the name of Hashem? We know it by ourselves!