"Mercy" in the Bible represents love, and the desire we have to do good things for people when we love them. The ultimate mercy, of course, comes from the Lord, who loves us constantly and infinitely, forgives us every wrong and works constantly to get us to choose heaven.

This verse, then, tells us that those who love others and act from that love will be fully receptive of the Lord's love, ultimately in heaven.

6314. As it is with light, so it is with the heat that is vital to a person's existence. In no way at all does that vital heat originate in the heat radiated by the sun in the world; rather, it originates in spiritual heat, which is love and radiates from the Lord. This heat is what angels have. Consequently the amount of vital heat a person has is determined by the amount of love he has. His body however is warmed by worldly heat, as is his sensory awareness within it; yet vital heat flows into that worldly heat and imparts life to it. Differences in the purity and intensity of this heat are akin to variations in the clarity of the light. This vital heat is what one should understand by the holy fires mentioned in the Word, and therefore heavenly loves are meant by those fires. But in a contrary sense that worldly heat is what one should understand by the fires of hell, and therefore hellish loves and the desires that go with them are meant when these fires are mentioned in the Word.