Heidegger's Bible Handbook: Nehemiah: Authorship, Part 2
2. The Author of the Book.
That Ezra is the Author of the Book, some ancients, Athanasius in his Synopsi, Chrysostom, and others, incorrectly assert, relying on that argument, that the Hebrews conjoin this book with the book of Ezra in one scroll. But, that Nehemiah, not Ezra, is the Author of the book, the first words of the book, דִּבְרֵ֥י נְחֶמְיָ֖ה, the words of Nehemiah, manifestly enough argue: and the same is evident from the diversity of style, which is easier and plainer in Nehemiah than in Ezra. Hence Nehemiah also sometimes speaks in the first person.