Confusedalot,
Listening to prophets means “whatever you desire for men to do to you, you. shall also do to them; for this is the law and the prophets.” (Mathew 7:12) Such altruistic attitude and action means doing good to others and refraining from doing harm to others! Working for the welfare of others with no thought of reciprocation would also bring gratitude and reciprocation from others. Even if that doesn’t happen in some cases, still it is beneficial because our very make-up is such that doing something nice for another person produces a pleasant feeling that behavioral economists call a warm glow and strengthens your immunity. University of Zurich researchers investigated how areas in the brain communicated to produce this feeling. (http://www.media.uzh.ch/en/Press-Releases/2017/Generosity.html) One’s attitude and action affect his body and mind, and even others who will respond accordingly; hence reaping happens without the intervention of God.