Translation
So then my brothers, boil with zeal to prophesy, and do not cut off the speaking in [unknown] tongues.
Paraphrase
Therefore, my brothers in the Lord, passionately desire that God give you the spiritual gift of admonishing and exhorting toward a more godly life, but at the same time, do not prohibit all speaking in tongues because that would curtail both the God-given, and the manmade, forms of it.
SOME WANTED PAUL TO PROHIBIT TONGUES ALTOGETHER
Because of the levels of self-centeredness, chaos and confusion present in the Corinthian congregation, I imagine that the letter sent to Paul may have asked him to prohibit all uses of tongues. In the mind of the person writing the letter, such a prohibition was the only way to deal with the problem that tongues had become. But Paul knew he could not make such a prohibition because there are proper uses of tongues which the Holy Spirit employs to great effect.