Jeremiah 29:1

Now these [are] the words of the letter that Jeremiah the
prophet sent from Jerusalem
The argument and tenor, the sum and substance, of an epistle, which the prophet Jeremiah, being at Jerusalem, wrote, under the inspiration of God, to his countrymen abroad, afterwards described; so the prophets under the Old Testament instructed the people, sometimes by their sermons and discourses delivered by word of mouth to them, and sometimes by letters and epistles; as did the apostles of the New Testament; and they were both ways useful and profitable to men: unto the residue of the elders which were carried away captive;
some perhaps dying by the way, and others quickly after they came to Babylon; some were left, who had been rulers or civil magistrates in Judea, and perhaps of the great sanhedrim: and to the priests, and to the prophets:
false prophets, as the Syriac version; for we read only of one true prophet that was carried captive, and that was Ezekiel; but of false prophets several: and to all the people, whom Nebuchadnezzar had carried away captive
from Jerusalem to Babylon;
which was eleven or twelve years before their last captivity thither. This was a catholic epistle, common to all the captives of every rank and class, age or sex.