Matthew 15, Mark 7

The scribes and Pharisees challenged the Savior -

"Why do thy disciples transgress the tradition of the elders? for they wash not their hands when they eat bread." (New Testament Matthew 15:2)

In turn the Savior asked them why at times failed to honor their parents and then quoted Isaiah -

"This people draweth nigh unto me with their mouth, and honoureth me with their lips; but their heart is far from me.
9 But in vain they do worship me, teaching for doctrines the commandments of men." (New Testament Matthew 15:8 - 9)

And then to the multitude he answered the scribes and Pharisees -

"Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth, this defileth a man." (New Testament Matthew 15:11)

He then explained to Peter and his apostles -

"...whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught?
18 But those things which proceed out of the mouth come forth from the heart; and they defile the man.
19 For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies:
20 These are the things which defile a man: but to eat with unwashen hands defileth not a man." (New Testament Matthew 15:17 - 20)

Much as the proverb of Solomon -

"...as he thinketh in his heart, so is he..." (Old Testament Proverbs 23:7)

Which also follows -

"...let virtue garnish thy thoughts unceasingly; then shall thy confidence wax strong in the presence of God..." (Doctrine and Covenants Section 121:45)

Paul taught the Phillipians -

"Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things." (New Testament Philippians 4:8)

Jacob taught -

"...Remember, to be carnally-minded is death, and to be spiritually-minded is life eternal." (Book of Mormon 2 Nephi 9:39)

I remember the talk given by Elder Boyd K. Packer where he relates our mind to a stage. I was impressed with the words that followed by Elder Bruce R. McConkie -

“To enable us to keep our minds centered on righteousness, we should consciously elect to ponder the truths of salvation in our hearts. Brother Packer yesterday pleaded with eloquence that we sing the songs of Zion in order to center our thoughts on wholesome things. I would like to add that we can also—after we have had the opening song—call on ourselves to preach a sermon. I have preached many sermons walking along congested city streets, or tramping desert trails, or in lonely places, thus centering my mind on the Lord’s affairs and the things of righteousness; and I might say they have been better sermons than I have ever preached to congregations.

If we are going to work out our salvation, we must rejoice in the Lord. We must ponder his truths in our hearts. We must rivet our attention and interests upon him and his goodness to us. We must forsake the world and use all our strength, energies and abilities in furthering his work.” (Bruce R. McConkie in CR, Oct. 1973, pp. 56–57.)

As we learn to control our thoughts and desires, in that our hearts and minds are not defiled, we will experience an inward purity that will enable us to draw upon the powers of heaven, remembering -

"...the rights of the priesthood are inseparably connected with the powers of heaven, and that the powers of heaven cannot be controlled nor handled only upon the principles of righteousness." (Doctrine and Covenants Section 121:36)