1 Corinthians 14:13-15
1Co 14:13 That is why the one speaking in another language should pray that he translates it.
1Co 14:14 If I am praying in another language, my spirit is praying, but my mind is not producing fruit.
1Co 14:15 What should be happening? I will pray in the spirit, but I will also pray with the mind. I will sing praise with the spirit, but I will sing praise also with the mind.
Paul is now addressing the difference between worshipping in a foreign language, and translating that worship so that others can be blessed by it. It is possible for a worshipper to pray or sing in a foreign language, and be blessed by the experience, so long as he or she understands what is being prayed or sung. Paul calls this activity praying or singing “with the spirit.”
But Paul has been discouraging this activity because it has lead to confusion and lack of edification in the Corinthian churches. Instead, he encourages praying and singing “with the mind” as well. That — in this context, is adding a translation to the prayer or song so as to edify those who could not understand the original utterance.
The fruitful mind is not one which merely understands, but one which explains what it understands, leading to the fruit of ministry to others.
LORD, make us fruitful worshippers, who seek to bless others by sharing our prayers and songs with them.