V.1-3 We are given abilities by the Holy Spirit in order to help other believers. To prophesy is to speak to them so as to teach, to encourage and comfort — to stir up, build up and bind up.
V.4-40 Instructions were given as to the use of the gift of speaking in tongues, that is, to be able to speak in other languages about the Lord. The Apostle insists on the necessity for making oneself understood, whether the man speaks, or sings or prays (vvs. 15-16).
V.18-19 Paul spoke in more languages than all, and wanted what was being said to be understood.
V.20 In the Corinthian assembly they were enjoying these gifts for themselves as evidence of the Spirit’s power, without anyone being helped. And this is of no value. Pride lifted up those who were showing off these gifts. Love doesn’t think of the individual speaking, but only of the help received by what was being said.