Derek Prince - Discovering the Gift of Prophecy
And then, prophesying just goes one step further. Prophesying is speaking in a language that is known words that are given by the Holy Spirit. They do not proceed from human understanding, they are given supernaturally by the Holy Spirit. The difference between interpreting and prophesying is that interpreting is preceded by an utterance in an unknown tongue and related to that utterance; prophesying simply starts out in a known language. Very frequently, I believe, in places where God’s people are gathered in assembly there will come an utterance in a tongue which is followed not by interpretation but by prophesy. The utterance in the tongue kind of calls God’s people to attention and prepares the way for the prophecy that follows.