This comment about psalms, hymns, and spiritual songs in Colossians 3:16 and Ephesians 5:19 is an important one that I regularly teach when I lecture on these passages:
If you were in Ephesus when Paul’s letter arrived, and you had a Bible in your church, it was a Septuagint. As you browsed through the Book of Psalms three terms would keep appearing in the titles and you would be quite familiar with them – psalmos, humnos and ode. In 67 Psalms the word psalmos is found eg Psalm 23; in 6 titles the word humnos appears eg Psalm 8; in another 35 Psalms ode is in the title eg Psalm 45. Furthermore, in 12 Psalms the words psalmos (psalm) and ode (song) are found together in the title e.g. Psalm 65, and in 2 titles psalmos (psalm) appears with humnos (hymn) eg Psalm 6. If you had studied the title of Psalm 76 all three terms are found in the Septuagint title, ‘For the end, among the hymns, a psalm for Asaph; a song for the Assyrian’. The Ephesian Christian would know that one Psalm could be a psalm and a song, or even a psalm and a song and a hymn together. All three terms were found in the titles of the Psalms and even in the title of one composition in the Book of Psalms. Paul exhorted them in biblical terms they were familiar with.
Now, I disagree with the author’s conclusion; I believe there are other reasons to warrant the singing of on non-inscripturated songs, but I do agree with this point.