I just wanted to share something I recently came across. A friend from Scotland asked me a question about John Nevay. In the process of not-finding a definite answer to his question, I eventually came across a volume of his sermons online. These are about the Covenant of Grace, and look to be rather good, although I haven't actually read them yet.
I did notice that the first sermon discusses the duty of singing Psalms and defends it against those who opposed singing, or opposed singing the Psalms specifically. Nevay seems to allow the singing of other Scripture songs besides the (150) Psalms, with which I would incline to disagree; but it is possible he just means those songs from the book of Psalms which are not technically Psalms (as according to the title.)
There are also a couple letters in the back of the book. Nevay had sent the Sermons back home to Scotland while banished in Holland, intending that they would be used in the persecuted fellowship meetings. They were finally printed in 1748, and probably often used for the same purpose once printed.