Albert Barnes
In the beginning ... Zedekiah - Probably a gloss put into the margin to explain “the same year,” from where it has crept into the text.
Gibeon - A city of priests Joshua 21:17. Hananiah was probably a priest as well as a prophet. He chose either a Sabbath or a new moon, that he might confront Jeremiah not only in the presence of the priests, but also of all the people. He used Jeremiah 28:2 the solemn formula which claims direct inspiration.
Within two full years - literally, In yet two years even days. Hananiah probably was induced to fix this date by the expectation that the confederacy then on foot would defeat Nebuchadnezzar.
Jeconiah - Zedekiah not being popular, the people would have preferred the young king, who had not reigned long enough to make enemies. Probably also Zedekiah had started for Babylon Jeremiah 51:59.
Then shall the prophet ... - Or, “shall be known as the prophet whom the Lord hath truly sent.”
The multitude would see in Hananiah’s act a symbol of deliverance.
I will cast thee - Rather, I send thee away. God had not sent Hananiah to prophesy, but He does now send him away to die.
Taught rebellion - As Nebuchadnezzar was Yahweh’s servant, to teach rebellion against him was to teach rebellion against his Master.