Jeremiah - Chapter 45
Longest and Shortest
Jeremiah started writing the Book that bears his name (or possibly Eicha - Lamentations - see chapter 36) during the reign of King Yehoyakim. At that time, he spoke to his disciple Baruch, sharing a prophecy G-d had spoken about him. Baruch had been pained that he did not attain prophecy himself, as other prophets' students had (e.g. Joshua and Elisha). G-d said that it was because He was about to tear down what He had built - namely the nation and the Temple. There is no need for Baruch to become a prophet, as there will soon be no one for him to whom to prophesy! But despite the evil to come, G-d will protect Baruch wherever he goes. (You will notice that in earlier chapters, we referred to Jeremiah's student as "the prophet Baruch." Indeed, Baruch is listed in the Talmud - Megillah 14b - among the 48 prophets whose words were retained for posterity. So, apparently, he did ultimately accomplish his goal.)
Nach fun fact: The longest Book in Tanach (the Hebrew Bible) is Tehillim - Psalms - at 150 chapters, with Isaiah a distant second at 66 chapters. Jeremiah, however, is the longest book in terms of word count. (Look at your Tanach - Jeremiah is thicker than Psalms!) At five verses, this is the shortest chapter in the longest book. (It is not the shortest in the Bible; Psalm 117 has a mere two verses.)