but be laying up for yourselves treasures in heaven, where neither moth nor rust doth tarnish、 and where thieves dig not through nor steal:” (Matthew 6:20, EMPH)

The Emphasized Bible [EMPH] translates the present tense here as “Be laying up for yourselves” where the ESV (for instance) translates it as “Lay up for yourselves.”  I prefer the EMPH translation because it emphasizes the ongoing process of laying up treasures in heaven.  This would seem to equate to the process of sanctification whereby God through circumstances and the Scriptures slowly changes us to be more like him as we struggle to put off the effects of sin which still seeks to grasp us in its tentacles.  When we come to faith in Christ we are free from the power of sin, but still must deal with sin’s presence in our lives.

The treasures that we lay up for ourselves in heaven come from following Christ and being obedient to him, by putting away sin, and putting on Jesus Christ. Paul, the apostle, will put it this way:

Let us walk properly as in the daytime, not in orgies and drunkenness, not in sexual immorality and sensuality, not in quarreling and jealousy. But put on the Lord Jesus Christ, and make no provision for the flesh, to gratify its desires.” (Romans 13:13–14, ESV)