In the Sermon on the Mount introduction (Matthew 5:2-12), Jesus’ focus is on the heart. Notice below, the red underlined words describe the inner quality and the blue points to the benefit.
To “hunger and thirst for righteousness” is to desire personal holiness and right living. The attitude of living a righteous life and honoring God in all we do, leads to true satisfaction. This is the person who is seeking after God and desiring to be right with Him. His/her desire for this will be satisfied some day when Jesus comes to set up His kingdom.
A “merciful” person forgives the guilty and has compassion on the needy and the suffering. This person wants to truly do unto others what he would want others to do unto him. They will receive mercy.
“The ‘pure in heart’ are those who are single-minded in their devotion to God and therefore morally pure inwardly. The ‘pure in heart’ can look forward to seeing God in the person of Messiah when He reigns on the earth (Ps. 24:3-4; Isa. 33:17; 35:2; 40:5).”
A righteous, merciful and pure heart is what God desires. He promises to meet and satisfy their every need, to give mercy, and will someday see Jesus in heaven where they will reign with Him. I love the verse in Psalms 51:10 where David cries out to God, “10Create in me a clean heart, O God, And renew a steadfast spirit within me.”
Let us examine our hearts every day before God, that we would have the right heart before Him. That is abundant living amidst the challenges and difficulties in life that we face.
 Constables Notes online, http://www.soniclight.com/constable/notes.htm