Be not proud - Both the symbols were of a nature very humiliating to the national self-respect.
Matthew Henry
Concise Bible Commentary
As the bottle was fitted to hold the wine, so the sins of the people made them vessels of wrath, fitted for the judgments of God; with which they should be filled till they caused each other's destruction. The prophet exhorts them to give glory to God, by confessing their sins, humbling themselves in repentance, and returning to his service. Otherwise they would be carried into other countries in all the darkness of idolatry and wickedness. All misery, witnessed or foreseen, will affect a feeling mind, but the pious heart must mourn most over the afflictions of the Lord's flock.
SDA Bible Commentary (limited)
Volume 1-7
15. Be not proud. Pride was Judah’s besetting sin (see v.9).