Therefore, one who speaks in a tongue should pray that he may interpret. For if I pray in a tongue, my spirit prays but my mind is unfruitful. What am I to do? I will pray with my spirit, but I will pray with my mind also; I will sing praise with my spirit, but I will sing with my mind also. Otherwise, if you give thanks with your spirit, how can anyone in the position of an outsider say “Amen” to your thanksgiving when he does not know what you are saying? For you may be giving thanks well enough, but the other person is not being built up. I thank God that I speak in tongues more than all of you. Nevertheless, in church I would rather speak five words with my mind in order to instruct others, than ten thousand words in a tongue. (1 Corinthians 14:13-19 ESV)
Paul corrects the self centered perspective of the Corinthian church on the use of tongues. Praying in tongues edifies the individuals praying (unless interpreted) thus is not a means of corporate edification or evangelism. When one prays in tongues, they may be thanking God but those gathered to worship together cannot thank God with them. The body of Christ, the church, gathers for mutual and corporate edification, not personal edification. So Paul concludes that he would rather communicate to instruct or edify others when the body is gathered.
Thanksgiving is the overflow of heart of the work of grace in our lives or the work of grace in the lives of others (2 Cor. 4:1; 9:11). As this grace is communicated to others in the body of Christ, thanksgiving to God increases and his fame spreads. We can thank God for his work in the lives of others because we are one body and share in that work of grace in the lives of others. That work is ours also by virtue of us being in Christ with them. The point I want to make is that if we are a people who are committed to faming the name of God, glorifying God, then we have a moral obligation to share the work of grace in our lives with others so that they can be encouraged and in turn give thanksgiving to God!