John Gill's Exposition of the Whole Bible
Jeremiah 28:17
So Hananiah the prophet died the same year,.... That he had delivered out his prophecy; in the same year in which Jeremiah said he should die; which proved him to be a false prophet, and Jeremiah to be a true one:
in the seventh month: it was two months after he had prophesied; for it was in the fifth month that he prophesied, and in the seventh he died; not after seven months, as Theodoret remarks, but in two months; so he that prophesied, that within two years what he foretold would come to pass, in two months time dies himself, according to the word of the Lord, and his prophecies die with him. The Jewish writers move a difficulty here, how he should be said to die the same year, when the seventh month was the beginning of another year; for the civil year of the Jews began from the seventh month, or the month Tisri; as their ecclesiastical year from the month Nisan or Abib. To solve this they observe a tradition, that he died the last day of the sixth month, or the eve of the new year; and ordered his sons and his servants, before his death, to hide it, and not bring him out to be buried till after the year was begun, to make Jeremiah a liar: to which agrees the Targum, both of the clause in Jeremiah 28:16; and this; the former of which it paraphrases thus,
"this year shall thou die; and in the other year (or the year following) thou shalt be buried;''
and this verse thus,
"and Hananiah the false prophet died this year, and was buried in the seventh month:''
but there was no occasion to raise such a difficulty, since it would have been enough to have verified the prediction, that he died any time within the twelve months from the date of it; and, besides, the solution makes the difficulty greater, and contradicts the very text, which says, he died in the seventh month.