In 1 Corinthians 14:15, Paul resolves the unfruitful mind by praying with both spirit and mind—the corrective to the problem stated here.

1 Corinthians 14:16 shows the practical problem: the ungifted person cannot say Amen because they don't understand the tongue.

In 1 Corinthians 14:19, Paul prioritizes five words with the mind over ten thousand in a tongue—highlighting the value of understanding for church edification.

1 Corinthians 14:4 explains that tongues edify the speaker—this shows the benefit of the spirit praying even when the mind is unfruitful.

Psalm 47:7 calls for singing praises with understanding, the OT background for Paul's insistence on engaging the mind in worship.