1 Corinthians 14:14-16

For if I pray in a tongue, my spirit prays, but my mind is unfruitful. So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding. Otherwise when you are praising God in the Spirit, how can someone else, who is now put in the position of an enquirer, say ‘Amen’ to your thanksgiving, since they do not know what you are saying?