The "last words" of David were, "The Spirit of the Lord spake by me, and his word was on my tongue" (11 Sam. 23:1-2).
The New Testament acknowledges that, Peter, quoting Psalm 41:9, says, "The scripture had to be fulfilled, which the Holy Spirit spoke before by the mouth of David" (Acts 1:16). Jesus quoted Psalm 110:1, prefacing it with, "For David himself said by the Holy Spirit"(Mark 12:36). Whether one says, "David himself says by the Spirit" or "The Spirit says by the mouth of David," two facts are affirmed: The words are from the mouth of David; the message is that of the Spirit of God. "The prophecy came not in old times by the will of men, but holy men of God spoke as they were moved by the Holy Spirit" (11 Pet. 1:21).
Jesus dictated seven letters to the seven churches of Asia. The apostle John took down the dictation as part of the vision our Lord gave him on the Isle of Patmos. The letters are a part of the book of Revelation. Each letter ends with the solemn charge, "He that has an ear, let him hear what the Spirit says to the churches"(Rev. 2:7, 11,17, 26 3:6, 13, 22).
In each letter, it is our glorified Lord who is identified as the speaker. It is John who obeyed the command to write. The resulting word, however, is "what the Spirit says." This is commensurate with what we are told elsewhere of the Spirit's work. The Spirit is not the originator of revelation, but is the conveyer and guarantor of it. "For he will not speak of himself, but whatever he hears he will speak" (John 16:13).
The writer of Hebrews, referring to the completeness and finality of our redemption, says, "The Holy Spirit is a witness to us," and quotes his "witness": "For after that he had said before ..." What follows is a quotation from Scripture, specifically Jeremiah 31:31,34. The witness of the Spirit to us is found in the words of Scripture.
We must still "hear what the Spirit says." We must not "quench the Spirit" (1 Thess. 5:19). We must follow the leading of the Holy Spirit (Rom. 8:14). It is a sad and dangerous mistake, however, to think these admonitions are teaching us to be sensitive to certain urges, influences and inner nudges. "The Spirit speaks expressly" through the words, promises and warnings of the apostles and other men inspired of the Spirit (I Tim. 4:14).
God does not leave us in uncertainty, guessing which hunches and inclinations are to be understood as his will for us. He commissioned his Spirit to speak to us clearly and finally in words, in Scripture. Cecil May, Preacher Talk