There are four primary scripture passages that are cited as evidence for praying in tongues: Romans 8:26; 1 Corinthians 14:4-17; Ephesians 6:18; and Jude verse 20. Ephesians 6:18 and Jude 20 mention “praying in the Spirit.” However, tongues as a prayer language is not a likely interpretation of “praying in the Spirit.”
Romans 8:26 “In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us with groans that words cannot express.”
Two key points make it highly unlikely that Romans 8:26 is referring to tongues as a prayer language. First, Romans 8:26 states that it is the Spirit who “groans,” not believers. Second, Romans 8:26 states that the “groans” of the Spirit “cannot be expressed.” The very essence of speaking in tongues is uttering words.
That leaves us with 1 Corinthians 14:4-17 and verse 14 especially: “For if I pray in a tongue, my spirit prays, but my mind is unfruitful.” First Corinthians 14:14 distinctly mentions “praying in tongues.” What does this mean? First, studying the context is immensely valuable. First Corinthians chapter 14 is primarily a comparison/contrast of the gift of speaking in tongues and the gift of prophecy. Verses 2-5 make it clear that Paul views prophecy as a gift superior to tongues. At the same time, Paul exclaims the value of tongues and declares that he is glad that he speaks in tongues more than anyone (verse 18).