1 Corinthians 14:13-14

Let him that speaketh in an [unknown] language pray that he may interpret. Let him pray that he may have the gift of interpretation also.

See PNT 1Co 12:10. Let him pray that he may understand what he utters, so as to explain it.
If I pray in an [unknown] tongue, etc. He does not understand, and only his spirit prayeth.
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