What comes out of the mouth springs from the heart, which is filled by thoughts of the mind. If the heart is filled with evil, caused by thoughts of evil, the mouth will spew out evil.
For we guard our heart by controlling what enters into our mind, to ensure our mouth only expels truth, love, and morality. Limiting availability to our heart starts by limiting availability to our mind. Our value is increased when we decrease the circle of people around us. This is similar to the value of a dime compared against the value of a nickel. The smallest circle has the greatest value. Qualify people and things with access to your person, thereby limiting negative thoughts allowed into the mind, thus altering what collects in the heart, which ultimately flows from the mouth. This increases our personal value without the diminishing effect of people and things that have no worth.
The Word of God and belief in His Son Jesus offers us thoughts of truth, peace, love, and hope when allowed to inhabit our minds. We have victory power over problems and deliverance over dilemmas when we nourish our thoughts with fruits of the spirit. God’s Word regulates our thought, which pours into our heart, and springs forth from our mouth.
Today, we decree and declare that we shall drink no more from the cesspool of worldly vomit, sent by Satan to feed us thoughts of evil, which fills the heart with an over abundance of evil, that floods from the mouth. We shall only allow good, upright, and just things into our mind. Giving us a divine understanding that Godly wisdom and knowledge springs forth when we drink of His Living Water. Our words are perfumed with the fragrance of His Word and become more pleasant when heard.
Matthew 12:33-34
33 “Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit.
34 O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.”
Job 13:4 
4 “But ye are forgers of lies, ye are all physicians of no value.”
Deuteronomy 18:22
22 “When a prophet speaketh in the name of the Lord, if the thing follow not, nor come to pass, that is the thing which the Lord hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not be afraid of him.”
Psalm 15:2
2 “He that walketh uprightly, and worketh righteousness, and speaketh the truth in his heart.”
Psalm 37:30
30 “The mouth of the righteous speaketh wisdom, and his tongue talketh of judgment.”
Psalm 144:11
11 “Rid me, and deliver me from the hand of strange children, whose mouth speaketh vanity, and their right hand is a right hand of falsehood:”
Proverbs 2:12
12 “To deliver thee from the way of the evil man, from the man that speaketh froward things;”
Proverbs 6:13
13 “He winketh with his eyes, he speaketh with his feet, he teacheth with his fingers;”
Proverbs 6:19
19 “A false witness that speaketh lies, and he that soweth discord among brethren.”
Proverbs 12:17-18
17 “He that speaketh truth sheweth forth righteousness: but a false witness deceit.
18 There is that speaketh like the piercings of a sword: but the tongue of the wise is health.”
Proverbs 16:13
13 “Righteous lips are the delight of kings; and they love him that speaketh right.”
Proverbs 21:28
28 “A false witness shall perish: but the man that heareth speaketh constantly.”