1 Corinthians 14
Gifts of Prophecy and Tongues
1Follow the way of love and eagerly desire spiritual gifts, especially the gift of prophecy. 2For anyone who speaks in a tongue[a] does not speak to men but to God. Indeed, no one understands him; he utters mysteries with his spirit. 3But everyone who prophesies speaks to men for their strengthening, encouragement and comfort. 4He who speaks in a tongue edifies himself, but he who prophesies edifies the church.
5I would like every one of you to speak in tongues,[c] but I would rather have you prophesy. He who prophesies is greater than one who speaks in tongues,[d] unless he interprets, so that the church may be edified. 6Now, brothers, if I come to you and speak in tongues, what good will I be to you, unless I bring you some revelation or knowledge or prophecy or word of instruction?
The highlighted scripture is important here. It states clearly that if you speaks in tongues make sure that the whole church understands you, what is the use if you speak in such a language that nobody understands you ? In my own Bible I have made an note stating that if you speak in tongues get an interpreter to explain to whoever wants to hear.
I don't think it is mandatory but the quoted scripture says "1Follow the way of love and eagerly desire spiritual gifts"
