On1Foot

Law 2:
These are the things for which the interest is collected from someone in this world and the principal remains for the world to come: idol worship, sexual prohibitions, and the shedding of blood; and gossip is equal to them all. A meritorious deed has principal and has interest as it says in the Torah: (Isaiah 3:10) "Hail the just person for it is good for them, for they shall eat the fruits of their works etc".