Albert Barnes Commentary Jeremiah 19:1

"Thus said Jehovah, Go, and buy a potter`s earthen bottle, and [take] of the elders of the people, and of the elders of the priests;" — Jeremiah 19:1 (ASV)

Get (that is, purchase) a potter’s earthen bottle. The “bottle” was a flask with a long neck and took its name from the noise made by liquids in running out.

The ancients. These “elders” were the regularly constituted representatives of the people (Numbers 11:16), and the organization lasted down to our Savior’s time (Matthew 26:47). Similarly, the priests also had their representatives (2 Kings 19:2). Thus accompanied by the representatives of Church and State, the prophet was to carry the earthen bottle, the symbol of their humble origin and frail existence, outside the walls of Jerusalem.