I once asked a religious –many years ago— if she could recommend a couple of books about the Psalms. She was about to give a series of talks over nine days on the subject of the Psalms. She couldn’t think of any! I decided not to attend the series.
There are, of course, about a million books on the Psalms (I probably exaggerate a little).
Herewith are a couple I like.
This is the commentary I rely on, most of all, for background information and reflection.
Be sure to use your reading glasses or a magnifying glass when consulting this commentary. It’s in fine print and exhaustive, literally a line-by-line explanation.
A more personal but insightful look at each Psalm.
This is the latest book by N. T. Wright and offers a good overview of the importance of the Psalms. This is not really a source for daily reflection on individual Psalms but rather makes the case for why daily praying of the Psalms by every Christian is essential. Many Psalms are, of course, discussed in support of his premise and you will pray the Psalms in a new light.
An excellent source for academic background on the poetry of the Psalms as well as their content. I think it’s more like a textbook. Instructive.