Recent scholars, on the other hand, without much show of reason, as it would appear, variously hold the Haftarah to have sprung from the sermon or homiletic exercise which accompanied the reading in the Pentateuch, and took its exordium (as Haftarah, by an extraordinary linguistic passage, adapted in a manner to the Mosaic text under consideration; or, again, they imagine the Haftarah to have taken its rise spontaneously during the exile itself, and that Ezra retained and enforced it in Palestine.
Source: wiktionary