Therefore let him that speaks in an unknown tongue pray that he may interpret.
Read Chapter 14
Cornelius a Lapide
AD 1637
Let him that speaketh . . . pray that he may interpret. Paul is here speaking of public prayer, in which one Prayer of Manasseh , even though a layman, inspired by the Holy Spirit, would offer up prayer in an audible voice before all, the others listening, and joining their prayers to his. This is the meaning, as appears from the following verses. But Chrysostom, Ambrose, and Anselm explain it thus: Let him pray that he may receive the gift of the interpretation of tongues, so as to make his own prayer intelligible to others.
Pray that he may interpret. In order that he may be rendered more useful to the Church, as the martyrs, who prayed for those particular gifts they saw would be most useful for themselves, or their neighbours. (Calmet)