Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe. Wherefore tongues are for a sign - The miraculous gift of tongues was never designed for the benefit of those who have already believed, but for the instruction of unbelievers, that they might see from such a miracle that this is the work of God; and so embrace the Gospel. But as, in the times of the prophet, the strange Babylonish tongues came in the way of punishment, and not in the way of mercy; take heed that it be not the case now: that, by dwelling on the gift, ye forget the Giver; and what was designed for you as a blessing, may prove to you to be a curse. For if, because ye have the gift of tongues, ye will choose for your own aggrandizement to use them in the public congregation where none understands them, God may curse your blessings.
Prophesying - Teaching the things of God in a known language is of infinitely more consequence than speaking in all the foreign tongues in the universe.