"Do not store up for yourselves treasures on earth, where moth and rust consume and where thieves break in and steal; but store up for yourselves treasures in heaven, where neither moth nor rust consumes and where thieves do not break in and steal.  For where your treasure is, there your heart will be also" ... "No one can serve two masters; for a slave will either hate the one and love the other, or be devoted to the one and despise the other.  You cannot serve God and wealth."

There is an excellent parallel teaching in Luke 12.13-21 which opens up this passage further.  Jesus commands and warns us to avoid greed even in the case of pursuing what is justly ours.  "One's life does not consist in the abundance of possessions."  James warns against piling up riches in 5.1-5.  "Your gold and silver have rusted, and their rust will be evidence against you" particularly when gained by fraud.  The orientation is also toward giving to those in need.  Once again from Luke: "to whom will this piled up wealth of yours go?"  And in 1 John 4.17 we hear "How does God's love abide in anyone who has the world's goods and sees a brother or sister in need and yet refuses help?"  We must share our goods with others.  We must not hoard it (because that leads to greed), we must not be greedy or stingy and we most certainly must not give it our heart.

If we do not give Christ our heart each day we will give it to the world.  Our attentions, love and concern always go somewhere!  There is a prevalent notion today that we can be a good Christian and still pursue wealth.  "You cannot serve God and wealth," Jesus says.  Serve God and if you gain wealth give it to others.  You will always be taken care of.  "Strive for the kingdom of God and all these things will be given to you as well." (Matthew 6.33)