Jarchi, and so the Midrash, understand this concluding clause as all imprecation of Job's; that if he had done otherwise than he had declared, he wishes that these might be his last words, and he become dumb, and never open his mouth more; but, as Bar Tzemach observes, the simple sense is, that his words were now completed and finished, just as the prayers of David, the son of Jesse, are said to be, Ps 72:20.
Bar Tzemach, et alii. hvab "herba foetens", Montanus, Bolducius; "spina foetida", Drusius; "vitium frugum", Junius & Tremellius, Piscator; "labrusca", Cocceius, Schultens.