Tongues are intended for a sign to unbelievers — To engage their attention, and convince them the message is of God. Whereas prophecy is not so much for unbelievers, as for the confirmation of them that already believe.
Related Commentaries of 1 Corinthians 14:22
1 Corinthians 14:22
22 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.