1 Corinthians 14:9-19 NIV

9 So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air.
10 Undoubtedly there are all sorts of languages in the world, yet none of them is without meaning.
11 If then I do not grasp the meaning of what someone is saying, I am a foreigner to the speaker, and he is a foreigner to me.1

References for 1 Corinthians 14:11

12 So it is with you. Since you are eager to have spiritual gifts,2 try to excel in gifts that build up3 the church.

References for 1 Corinthians 14:12

      13 For this reason anyone who speaks in a tongue should pray that he may interpret what he says.4

      References for 1 Corinthians 14:13

          14 For if I pray in a tongue, my spirit prays,5 but my mind is unfruitful.

          References for 1 Corinthians 14:14

              15 So what shall I do? I will pray with my spirit,6 but I will also pray with my mind; I will sing7 with my spirit, but I will also sing with my mind.

              References for 1 Corinthians 14:15

                  16 If you are praising God with your spirit, how can one who finds himself among those who do not understanda say "Amen"8 to your thanksgiving,9 since he does not know what you are saying?

                  References for 1 Corinthians 14:16

                  17 You may be giving thanks well enough, but the other man is not edified.10

                  References for 1 Corinthians 14:17

                      18 I thank God that I speak in tongues more than all of you.
                      19 But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue.11

                      References for 1 Corinthians 14:19