But if they are prophets, and if the word of the LORD is with them, let them now make intercession to the LORD of hosts, that the vessels which are left in the house of the LORD, in the house of the king of Judah, and at Jerusalem, do not go to Babylon.' Jeremiah 27:18
Remember that we are citing guidelines, not commands, for the gift of prophecy. Prophets can get prayers answered. God answers prayers in accord with His will, and if a prophet knows God's will, he will know what to pray for.
You will sometimes find a person who is not being used by God, who suddenly claims to be a prophet and demands obedience. Forget it. If that person really knows God's will, he or she will be getting prayers answered.