Recalling an argument made by a pastor who was deeply fascinated by Rabbinical literatures, that he did not think David as a prophet. At that time, I was just wondering if he was just restricted by what he "memorized" from textbooks about the number of prophets in old testament, major/minor prophets, and thus do not wish to consider the true purpose and definition of prophet.
After reading Acts 2:30 today, I looked up John Gill's Commentary on this, and realized that it was a Judaism thing to separate Holy writings from Prophetic writings. Considering David being influenced by the Spirit, therefore, they place those like him, Solomon, Daniel to not be "strictly and properly prophets". However, another Rabbi, Kimchi, allowed David to be a prophet, a name for those who are "men of God".
I know what this pastor would respond, even though we never discussed this further. He would reply as a someone trained in Christian seminary but too influenced by the Jewish literatures, that it is just the function of prophet that was meant in Acts, not the actual prophet.
For Christians, a prophet is God's spokesman who points to the coming of Christ and to call others to repentance. And we only make use of the function of prophet today because the proper office of a prophet is no more when the Bible is completed. God speaks to us through the Bible and the Bible alone.
This is just a minor issue. But I believe it is important in the sense for those who care to actually discern the importance of very small things as well as the whole picture.