In the Reformed Westminster Confession of Faith (1646) “Of the Holy Scripture” paragraph 10, it states:
The supreme judge by which all controversies of religion are to be
determined, and all decrees of councils, opinions of ancient writers,
doctrines of men, and private spirits, are to be examined, and in
whose sentence we are to rest, can be no other but the Holy Spirit
speaking in the Scripture.
Here "private spirits" are placed on the same level as "decrees of councils," "opinions of ancient writers," and "doctrines of men." All of these are to be subordinate to "the Holy Spirit speaking in Scripture."
According to author Byron Curtis, "...in mid-seventeenth-century England there was an established meaning to the phrase ‘private spirits' denoting personal revelations." Curtis notes evidence from literature close in time, showing that the term "private spirits" was commonly understood to mean "personal revelations" that people received from the Holy Spirit.
Around that same period of time, the Lutherans agreed with that understanding. For example, Johannes Andreas Quenstedt (August 13, 1617 – May 22, 1688) was a German Lutheran dogmatician in the Lutheran scholastic tradition. He writes:
We must distinguish between revelations which pertain to, or attack,
an article of faith, and those which concern the state of the Church
or the State, social life, and future events; the first we repudiate;
the latter, however, some hold, are not to be urged with any necessity
of believing, nevertheless are not to be rashly rejected. (Francis Pieper,
Christian Dogmatics, Vol. 1, p. 211)