Romans 10:14-15

How, then, shall they call on him in whom they have not believed? And how shall they believe in him of whom they have not heard? And how shall they hear without a preacher?

Ephesians 4:29

Let no impure speech come out of your mouth, but whatever is good for needful edification, that it may give grace to the hearers:

Treasury of Scripture Knowledge

Summary

There is gold, and a multitude of rubies: but the lips of knowledge are a precious jewel.

Bible References

But

Romans 10:14
How, then, shall they call on him in whom they have not believed? And how shall they believe in him of whom they have not heard? And how shall they hear without a preacher?
Ephesians 4:29
Let no impure speech come out of your mouth, but whatever is good for needful edification, that it may give grace to the hearers: