The first part is found here: https://memoirandremains.wordpress.com/2012/12/06/how-must-we-govern-our-tongues-part-1/
C. The tongue possesses a capacity for sin like no other aspect of our lives: It is a “world of iniquity” (James 3:6). It injures the speaker, the hearer, and the one of who the tale is told.
1. The tongue flies at everyone and everything: The one who would not strike an authority will slander the same. As Peter writes of the false teachers, “Bold and willful, they do not tremble as they blaspheme the glorious ones,” 2 Peter 2:10 (ESV). Jude adds, “9 But when the archangel Michael, contending with the devil, was disputing about the body of Moses, he did not presume to pronounce a blasphemous judgment, but said, “The Lord rebuke you.” 10 But these people blaspheme all that they do not understand, and they are destroyed by all that they, like unreasoning animals, understand instinctively” Jude 9–10 (ESV).
2. The tongue, like an uncontrollable water house, flies about in every vein of sin: The tongue will lie to destroy or flatter; the tongue can poison whether we are in a good or bad mood; it is always ready to destroy and has a means for every opportunity and time.
3. It can destroy like nothing else: it can destroy a person’s reputation, marriage, job, life. Its darts sink deepest, and its wounds heal slowest of any other. (Psalm 69:19, 21.) And in this respect the tongue may be expressed not only by a rod, by a scourge, by a sword, but by the sting and poison of a serpent, to note the anguish of its biting, and the difficulty of its curing. (Psalm 140:3; 42:10; Prov. 14:3.)
D. What Conclusions Should We Draw From This?
1. We should do everything necessary to control the tongue: we should treat it like a dog known to bite; or, (as West puts it)That in all reason and righteousness such a member should be strictly kept-in, even as an ox that is wont to goring.
2. That if we keep it not in, God will cut it out:: God will need to eventually correct his children to prevent their sin. Thus, with Ananias and Sapphira, God brought their death to stop their sin (Acts 5:1-10). God punished the unquestioned unbeliever Herod for his sin (Acts 12:23).
II The Excellence of the Tongue: When properly governed, the tongue has power to do excellent good.
A. The Tongue Permits to Speak to God: Consider throughout the Psalms, the psalmists call out to God to see his circumstances, to rescue from one’s enemies (Psalm 3); to hear his prayer (Psalm 5); to cease from correction (Psalm 6); to remember and come near (Psalm 13); et cetera. The prophets set forth many such prayers (Habakkuk 1:1-3).
B. The Tongue permits us to praise and thank God: The Psalms are again filled with such praise. And example of such praise, remembrance, and thanksgiving can be found in Psalm 105; see, e.g., Psalm 51:15, 145:21).
C. To Bring Rebels Into Reconciliation With God: 2 Corinthians 5:16–21 (ESV)
16 From now on, therefore, we regard no one according to the flesh. Even though we once regarded Christ according to the flesh, we regard him thus no longer. 17 Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. 18 All this is from God, who through Christ reconciled us to himself and gave us the ministry of reconciliation; 19 that is, in Christ God was reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation. 20 Therefore, we are ambassadors for Christ, God making his appeal through us. We implore you on behalf of Christ, be reconciled to God. 21 For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.
D. Believers can encourage, exhort, comfort, bless one-another: Proverbs 10:21 (ESV)The lips of the righteous feed many, but fools die for lack of sense. Proverbs 10:11 (ESV) The mouth of the righteous is a fountain of life, but the mouth of the wicked conceals violence. See, also Proverbs 12:18 & 15:4. The entire Bible is a book of words. The proclamation of Jesus lies at the heart of the Christian’s duty, Matthew 28:18-20.
1. The Advantage to Others: Since our tongues can bring such good, we should use diligence to bring our tongues to order.
2. God Delights in Ordering our Tongues: God delights to do the things he commands. 16 Then those who feared the LORD spoke with one another. The LORD paid attention and heard them, and a book of remembrance was written before him of those who feared the LORD and esteemed his name. 17 “They shall be mine, says the LORD of hosts, in the day when I make up my treasured possession, and I will spare them as a man spares his son who serves him. Malachi 3:16–17 (ESV)
III It is the Glory of a Man to Govern His Tongue:
A. General Observations:
1. Not Speaking: Proverbs 17:28 (ESV) Even a fool who keeps silent is considered wise; when he closes his lips, he is deemed intelligent.
2. Foolish Speaking Makes a Fool: Proverbs 10:18–19 (ESV) 18 The one who conceals hatred has lying lips, and whoever utters slander is a fool. 19 When words are many, transgression is not lacking, but whoever restrains his lips is prudent.
3. Control is Mark Of Godliness: James 3:2 (ESV) For we all stumble in many ways. And if anyone does not stumble in what he says, he is a perfect man, able also to bridle his whole body.
4. Impotence: Whereas, on the other hand, he is fit for nothing that has a loose and licentious tongue; and it is generally a token of an impotent man.
5. A Worse Friend: As bad a neighbour as he is, he is yet a worse friend: he trifles away our time, he tires our patience, he betrays our trusts: there can be no confidence in him; we must still be upon the watch; one may as well make a whole town our friend as such an one. But yet, too, a much worse relation he makes: it is next [to] dwelling in a mill, to dwell with him; his clack is always going, only not in so good tune and order as that we allude to. The wise man could not think of a condition so intolerable as the being yoked with such a relation (Prov. 25:24).
B. The Measure of Right Government
1. Don’t Be Too Silent: Though it is rare, there are times when we should speak.
a. We should speak when justice will be denied or obstructed. When our silence permits wickedness to flourish, we have sinned. Jeremiah 1 gives a vivid picture of God requiring speech.
b. We should be speak to promote love, comfort or good. There many commands to affirmatively speak to our fellows: Hebrews 3:12-13; Matthew 28:18-20; Acts 4:19-20; Lev. 19:17; Matt. 18:15-20.
c. If our own spirits be soured by it.—Words kept-in are, many times, like humours struck-in,—go to the heart and offend the vital parts. Maliciousness, censoriousness, are often so fed; vent might give relief in this case, and be the only means for our cure, immoderately and discreetly given. Proverbs 28:13 (ESV) 13 Whoever conceals his transgressions will not prosper, but he who confesses and forsakes them will obtain mercy.
d. Where it would offend those about us: There are times when keeping silence will be a grief to those about us: “you had as good send your horse among them, if you will not converse like a man with them.”
e. If God’s cause requires public testimony: Matthew 21:15-16; Luke 19:40.
2. Don’t Speak Too Much:
a. When talking excludes thinking: Don’t talk if you have not thought: “but it is an intolerable presumption upon men to entertain them with words more crude than our belches, that we fetch not so low as our breath, and that little differ from an ass’s braying.”
b. When we should listen, particularly where someone more appropriated and fitted to the occasion can and will speak. James 1:19 (ESV) Know this, my beloved brothers: let every person be quick to hear, slow to speak, slow to anger;
c. When talking stops work – our work, the work of others, or the honor of Christ. These are people who keep others distracted at work and away from their work. 1 Timothy 5:13 (ESV) 13 Besides that, they learn to be idlers, going about from house to house, and not only idlers, but also gossips and busybodies, saying what they should not.
3. Wisdom lies between these Extremes
 West has the quaint line, “The tongue is a very mischievous outlaw, no member like it, if it get loose.”
 There is the strange thought of why does God ordain Psalm of himself in the Psalms. C.S. Lewis provides an extraordinary and insightful observation, discussed here, http://www.enjoyinggodministries.com/article/27-c-s-lewiss-most-important-discovery/