How a Christian must speak with Godliness based in the Bible?

We must remember that these body parts that do trangressions:

Eyes - Matthew 5:29

Hands - Matthew 5:30

But the worst of it is the heart - Jeremiah 17:10

This is where evil thinking, killings, adultery, fornication, stealing, bear false witness against your neighbor and blaphemies (read Matthew 15:19)

So the heart is the root of evil.

But the tongue can do a lot of trangressions

How to speak with Godliness?

1) Don't use the name of the Lord your God in vain - Exodus 20:7

2) Refraining his lips is a wise man - Proverbs 10:19 (meaning he is not tactless)

3) "But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation." (James 5:12)

4) "Boast not thyself of to morrow; for thou knowest not what a day may bring forth." (Proverbs 27:1)

it is because we don't know what will happen tomorrow (it is in James 4:13-14)

The main reason that we must follow this is:

Matthew 12:36 But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.

12:37 For by thy words thou shalt be justified, and by thy words thou shalt be condemned. (Take note of this verse 37)

5) "Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers." (Ephesians 4:29)

6) "Neither filthiness, nor foolish talking, nor jesting, which are not convenient: but rather giving of thanks." (Ephesians 5:4)

7) "Put away from thee a froward mouth, and perverse lips put far from thee." (Proverbs 4:24)

8) If you promise to do something, say GOD WILLING which is written in James 4:15.

because we don't know what will happen tomorrow (it is in James 4:13-14)

and also "And this will we do, if God permit." (Hebrews 6:3)

9) We must know how to control our lips when speaking it is because:

"Whoso keepeth his mouth and his tongue keepeth his soul from troubles. " (Proverbs 21:23)

10) If we are tactless, the Bible says this:

"If any man among you seem to be religious, and bridleth not his tongue, but deceiveth his own heart, this man's religion is vain." (James 1:26)

11) "But if ye bite and devour one another, take heed that ye be not consumed one of another. " (Galatians 5:15)

12) By your own way of communicating, "Give none offence, neither to the Jews, nor to the Gentiles, nor to the church of God:" (1 Corinthians 10:32)