1st Corinthians 14:6

3 But he who prophesies speaks to men for their edification, exhortation, and consolation.

4 He who speaks in another language edifies himself, but he who prophesies edifies the assembly.

5 Now I desire to have you all speak with other languages, but rather that you would prophesy. For he is greater who prophesies than he who speaks with other languages, unless he interprets, that the assembly may be built up.

6 But now, brothers, if I come to you speaking with other languages, what would I profit you, unless I speak to you either by way of revelation, or of knowledge, or of prophesying, or of teaching?

7 Even things without life, giving a voice, whether pipe or harp, if they didn`t give a distinction in the sounds, how would it be known what is piped or harped?

8 For if the trumpet gave an uncertain voice, who would prepare himself for war?

9 So also you, unless you uttered by the tongue words easy to understand, how would it be known what is spoken? For you would be speaking into the air.