Charles H. Spurgeon on Psalms 41:13

How ancient the division is cannot now be clearly ascertained. Jerome, in his epistle to Marcella, and Epiphanius speak of the Psalms as having been divided by the Hebrews into five books, but when this division was made they do not inform us. The forms of ascription of praise, added at the end of each of the five books, are in the Septuagint version, from which we may conclude that this distribution had been made before that version was executed. It was probably made by Ezra, after the return of the Jews from Babylon to their own country, and the establishment of the worship of God in the new temple, and it was perhaps made in imitation of a similar distribution of the books of Moses. In making this division of the Hebrew Psalter, regard appears to have been paid to the subject matter of the Psalms. John Calvin.