“The German Rendering. The German language was divided into as many dialects as tribes and states, and none served as a bond of literary union. Saxons and Bavarians, Hanoverians and Swabians, could scarcely understand each other. Each author wrote in the dialect of his district, Zwingli in his Schwyzerdütsch. "I have so far read no book or letter," says Luther in the preface to his version of the Pentateuch (1523), in which the German language is properly handled. Nobody seems to care sufficiently for it; and every preacher thinks he has a right to change it at pleasure, and to invent new terms." Scholars preferred to write in Latin, and when they attempted to use the mother tongue, as Reuchlin and Melanchthon did occasionally, they fell far below in ease and beauty of expression.
Luther brought harmony out of this confusion, and made the modern High German the common book language. He chose as the basis the Saxon dialect, which was used at the Saxon court and in diplomatic intercourse between the emperor and the estates, but was bureaucratic, stiff, heavy, involved, dragging, and unwieldy. He popularized and adapted it to theology and religion. He enriched it with the vocabulary of the German mystics, chroniclers, and poets. He gave it wings, and made it intelligible to the common people of all parts of Germany.”

Which Greek and Hebrew texts of the Bible did Luther use?