Nadere Reformatie on Psalmody

One may read an extract from The Christian's Reasonable Service by Wilhelmus à Brakel on singing, including his views on exclusive psalmody, here.

The decision of the Dutch Synods has been very correct indeed, namely, that none other but the Psalms of David are to be used in the churches.

Note: à Brakel appears not be referring to Article 69 of the Church Order of the 1618-1619 Synod of Dort, which states:

In the Churches only the 150 Psalms of David, the Ten Commandments, the Lord's Prayer, the Twelve Articles of Faith, the Song of Mary, that of Zacharias, and that of Simon shall be sung. It is left to the individual Churches whether or not to use the hymn "Oh God! who art our Father." All other hymns are to be excluded from the Churches, and in those places where some have already been introduced they are to be removed by the most suitable means.

but rather to earlier synodical decisions of the Dutch Reformed Church (cited by Hendrik de Cock in his famous treatise on psalmody, and Abraham Van De Velde in his history of the Dutch Golden Age) such as:

The Psalms of David, in the edition of Petrus Dathenus, shall be sung in the Christian meetings of the Netherlands Churches (as has been done until now), abandoning the hymns which are not found in Holy Scripture. --National Synod of Dort, 1578, Art. 76.

Only the Psalms of David shall be sung in the church, omitting the hymns which one cannot find in Holy Scripture. --National Synod of Middelburg, 1581, Art. 51.

The Psalms of David shall be sung in the churches, omitting the hymns which one does not find in Holy Scripture. --National Synod of Gravenhage, 1586, Art. 62.