1. Be silent in the heat of anger
A quick-tempered man does foolish things, and a crafty man is hated.
2. Be silent When you don't have all the facts
He who answers before listening-- that is his folly and his shame.
3. Be silent When you haven't verified the story
On the testimony of two or three witnesses a man shall be put to death, but no one shall be put to death on the testimony of only one witness.
4. Be silent If your words will offend a weaker person
1 Corinthians 8:11
So this weak brother, for whom Christ died, is destroyed by your knowledge.
5. Be silent When it is time to listen
A wise son heeds his father's instruction, but a mocker does not listen to rebuke.
6. Be silent When you are tempted to make light of holy things
Do not be quick with your mouth, do not be hasty in your heart to utter anything before God. God is in heaven and you are on earth, so let your words be few.
7. Be silent When you are tempted to joke about sin
Fools mock at making amends for sin, but goodwill is found among the upright.
8. Be silent If you would be ashamed of your words later
9. Be silent If your words would convey the wrong impression
A man of knowledge uses words with restraint, and a man of understanding is even-tempered.
10. Be silent If the issue is none of your business
Each heart knows its own bitterness, and no one else can share its joy.
11. Be silent When you are tempted to tell an outright lie
Put away perversity from your mouth; keep corrupt talk far from your lips.
12. Be silent If your words will damage someone else's reputation
A scoundrel plots evil, and his speech is like a scorching fire.
13. Be silent If your words will damage a friendship
A perverse man stirs up dissension, and a gossip separates close friends.
14. Be silent When you are feeling critical
With the tongue we praise our Lord and Father, and with it we curse men, who have been made in God's likeness.
15. Be silent If you can't say it without screaming it
Like a city whose walls are broken down is a man who lacks self-control.
16. Be silent If your words will be a poor reflection of the Lord or your friends and family
1 Peter 2:21-23
21 To this you were called, because Christ suffered for you, leaving you an example, that you should follow in his steps.
22 "He committed no sin, and no deceit was found in his mouth."
23 When they hurled their insults at him, he did not retaliate; when he suffered, he made no threats. Instead, he entrusted himself to him who judges justly.
17. Be silent If you may have to eat your words later
The tongue has the power of life and death, and those who love it will eat its fruit.
18. Be silent If you have already said it more than one time
A foolish son is his father's ruin, and a quarrelsome wife is like a constant dripping.
19. Be silent When you are tempted to flatter a wicked person
Whoever says to the guilty, "You are innocent"-- peoples will curse him and nations denounce him.
20. Be silent When you are supposed to be working instead
All hard work brings a profit, but mere talk leads only to poverty.
He who guards his mouth and his tongue keeps himself from calamity.