Question: Who wrote the book of Psalms? Was it entirely written by King David?

Answer: The Talmud (Oral Teachings of Torah that were eventually written down around 1800 years ago) teaches that King David composed and compiled the Psalms. Those Psalms explicitly attributed to him, and most of the anonymous ones (but not all), were written by David, or in some cases to David by his court composers. The Talmud (Bava Basra 14b) mentions that there were ten earlier composers from whose work David compiled to make many of the Psalms. It says, “David wrote the Book of Psalms, including in it the work of the elders Adam, Malkizedek, Abraham, Moses, Heman, Jeduthun, Asaph, and the three sons of Korah.”. The text and order of the Psalms, like all books of the Kesuvim, was inspired by God.

Rabbi Joe Kolakowski