1Cor 14:13

“You see that the barbarian philosophy professes deeds, not words. The apostle thus speaks: "So likewise ye, except ye utter by the tongue a word easy to be understood, how shall ye know what is spoken? for ye shall speak into the air. There are, it may be, so many kind of voices in the world, and none of them is without signification. Therefore if I know not the meaning of the voice, I shall be unto him that speaketh a barbarian, and he that speaketh shall be a barbarian unto me." And, "Let him that speaketh in an unknown tongue pray that he may interpret."”

“"Wherefore let him that speaketh in a tongue pray that he may interpret." Here he shows that it is in their power to obtain the gift. For, "let him pray," saith he, i.e., "let him contribute his own part," since if thou ask diligently, thou wilt surely receive. Ask accordingly not to have the gift of tongue only, but also of interpretation, that thou mayest become useful unto all, and not shut up thy gift in thyself alone.”

“Wherefore let him that speaketh in an unknown tongue,.... The Hebrew, or any other, the gift of speaking with which is bestowed upon him: pray that he may interpret; that he may have also the gift of interpretation of tongues; for as has been before hinted, these two gifts were distinct; and a man might have the one, and not the other; a man might speak in an unknown tongue, so as to understand himself, what he said, and be edified, and yet not be capable of translating it at once into the common language of the people; and if he could not do this, he would not excel in his gift to the edification of the church; whereas if he could interpret he would, and therefore, above all things, he should pray to the Father of lights, the giver of every good and perfect gift, that he might be furnished with this also.”

“Pray that he may interpret - Let him who speaks or reads the prophetic declarations in the Old Testament, in that tongue in which they were originally spoken and written, pray to God that he may so understand them himself, and receive the gift of interpretation, that he may be able to explain them in all their depth and latitude to others.”

“Explain, "Let him who speaketh with a tongue [unknown] in his prayer (or, when praying) strive that he may interpret" [ALFORD]. This explanation of "pray" is needed by its logical connection with "prayer in an unknown tongue" (Co1 14:14). Though his words be unintelligible to his hearers, let him in them pray that he may obtain the gift of interpreting, which will make them "edifying" to "the church" (Co1 14:12).”