Treasures: Either in heaven or on earth
In Matthew 6:19-21 Jesus contrasts treasures on earth with treasures in heaven. He tells his disciples not to store up treasures on earth. Those treasures will not last: moths or other insects destroy treasured clothes; thieves break in and steal treasured possessions.
The word treasures suggests expensive clothes or jewelry, luxurious houses, or lots of land or money. If one is focused on those treasures, their heart (their thoughts, wants, and joys) will pursue and take pride in such treasures.
In contrast, pure hearts focused on the treasures in heaven would sell or give away expensive treasures on earth in order to show mercy to the most destitute. Jesus commands this for all disciples in Luke 12:33, in order for them to have treasure in heaven. Heavenly treasure for the pure in heart will be to see God in heaven (Mt. 5:8); heavenly treasure for those who show mercy will be to receive mercy from God (Mt. 5:7).
For many American disciples, a change of heart will mean “downward mobility”–though usually not destitution–rather than the upward mobility of a greedy world. Instead of seeking more expensive houses or cars or land or clothes or jewelry, disciples will sell expensive treasures and live more simply. They can then give generously to the most destitute; even some of the poor have modest means to help the most destitute.
Since numerous charities and philanthropies pay social workers and administrators middle-class salaries using donations for the poor, it is better to give to the destitute directly–or via someone who gets paid little or nothing for helping. This would mean seeking out, and getting to know, some of the poorest people, both near and far; and it could mean discovering (and enabling) those who quietly and sacrificially care for them. James 1:27 says pure religion reaches out to visit and help widows and orphans (examples of the poorest poor at that time).