“Having different gracious gifts, according to the grace given us: if prophecy, according to the proportion of faithfulness…” (Romans 12:6, DBH). If Hart’s translation is correct, then one should prophesy in proportion to one’s demonstrated faithfulness, not according to one’s faith, the latter word being the majority translation in this context vacant of meaning.
In other words, only prophesy if your deeds warrant you time with the microphone.