Melito, to his brother Onesimus, greeting: Since thou hast often, in thy zeal for the word, expressed a wish to have extracts made from the Law and the Prophets concerning the Saviour, and concerning our entire faith, and hast also desired to have an accurate statement of the ancient book, as regards their number and their order, I have endeavored to perform the task, knowing thy zeal for the faith, and thy desire to gain information in regard to the word, and knowing that thou in thy yearning after God, esteemeth these things above all else, struggling to attain eternal salvation. Accordingly when I came East and came to the place where these things were preached and done, I learned accurately the books of the Old Testament, and send them to thee as written below. Their names are as follows: Of Moses, five books: Genesis, Exodus, Numbers, Leviticus, Deuteronomy; Jesus Nave, Judges, Ruth; of Kings, four books; of Chronicles, two; the Psalms of David, the Proverbs of Solomon, Wisdom also, Ecclesiastes, Song of Songs, Job; of Prophets, Isaiah, Jeremiah; of the twelve prophets, one book; Daniel, Ezekiel, Esdras.
NPNF2, Vol. 1, Eusebius, Church History IV.26.13-14.