Romans 10:14-15

[But] how can they appeal to Him if they have not [first] believed in Him? And how can they believe in Him if they have not [first] heard [about Him]? And how can they hear [about Him] if there is no preacher?

Ephesians 4:29

Do not allow unwholesome [Note: The Greek word for "unwholesome" is "rotten, diseased"] language to come from your mouth, but only what is helpful for building up those who need it, so that you can impart favor [i.e., benefit] to those who listen [to you].

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
[But] how can they appeal to Him if they have not [first] believed in Him? And how can they believe in Him if they have not [first] heard [about Him]? And how can they hear [about Him] if there is no preacher?
Ephesians 4:29
Do not allow unwholesome [Note: The Greek word for "unwholesome" is "rotten, diseased"] language to come from your mouth, but only what is helpful for building up those who need it, so that you can impart favor [i.e., benefit] to those who listen [to you].