"Who may ascend into the hill of the Lord?
Or who may stand in His holy place?
He who has clean hands and a pure heart..." Psalm 24:3-4

"Blessed are the pure in heart: for they shall see God" Matthew 5:8

BLESSED: the object of God's favor--
And why?
They are chosen:
"Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ, just as He chose us in Him before he foundation of the world, that we should be holy and without blame before Him in love." Ephesians 1:3-4

They are forgiven:
"Blessed is he whose transgression is forgiven, Whose sin is covered.
Blessed is the man to whom the Lord dose not impute iniquity, And in whose spirit there is no guile. Psalm 32:1-2

They are justified:
"Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ." Romans 5:1

They are instructed:
"Blessed is the man whom You instruct, O Lord, And teach out of Your law." Psalm 94:12

They keep God's word:
"Blessed is he who reads and those who hear the words of this prophecy, and keep those things which are written in it; for the time is near."
Revelation 1:3

THE PURE IN HEART;
I quote Martyn Lloyd-Jones from "Studies in the Sermon on the Mount,"
"Blessed are those who are pure, not merely on the surface but in the center of their being and at the source of their every activity."

A pure heart is without hypocrisy. As Lloyd-Jones tells us, it is 'single'.
And speaking of single, what does Jesus say in Luke when speaking of the eye?
"The light of the body is the eye; therefore when thine eye is single, thy whole body also is full of light; but when thine eye is evil, thy body also is full of darkness." Luke 11:34 "If thy whole body therefore be full of light, having no part dark, the whole shall be full of light..." Vs. 36 So we see, therefore, a pure heart is not divided, but it is single.
Though Jesus is speaking of earthly treasures in Matthew 6:19-24 verse 24 could apply here as well, "No one can serve two masters; for either he will hate the one and love the other, or else he will be loyal to the one and despise the other, You cannot serve God and mammon."

God looks at the heart:
"...For the Lord does not see as man sees, for man looks at the outward appearance, but the Lord looks at the heart." 1 Samuel 16:7

God knows the heart:
"...For He knows the secrets of the heart." Psalm 44:21

God enlightens the heart:
"For it is the God, who commanded light to shine out of darkness who has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ." 2 Corinthians 4:6

THEY SHALL SEE GOD:
"...God is light and in Him is no darkness at all..." 1 John 1:5 Light and darkness do not mix, therefore, we must walk in the light as He is in the light, we to do so in holiness and with a pure undivided heart that is unto God.
Hebrews 12:14 tells us,
"Make every effort to live in peace with all men and to be holy; without holiness no one will see the Lord."

Lord we lift our hearts to You knowing that our relationship with You is a
heart relationship, so have Your perfect way in each of us.   Teach us Lord
to know, love and worship You more perfectly.  You alone are our heart's desire!  Amen