Guru nanaki ji father knew that nanak ji like to communicate with people. So he decided that if nanak ji was to learn anyway to earn money, it can be done through trading. So one day, guru nanak's father gave bhai bala twenty rupees and said, "Go with nanak and buy some good from market and them sell them at profitable rate."So bhai bala and nanak went to market to buy some goods. As they had passed ten miles from their village, they come across a group of hermits who were sitting under a tree. Seeing them nanak ji stopped bhai bala and said, "Father asked us to make some profitable transaction and nothing can be more profitable than to feed these hermits.I can't go forward leaving such great opportunity to make true profitable transaction."Nanak ji took all the money from bhai bala and offered that money to them saying, "I offer this in your service.."Head of that hermit group replied, "Son, this money is of no use for us as we never go to any village or town.we always stay here in jungle.. if you offer us a meal, we will accept it.."Then nanak ji and bhai bala went to near by village to get meals for hermits and with remaining money he purchased clothes for hermits. Nanak ji offered all that to group of hermits and left for home empty handed. 
Earning more money can be profitable but true profit lies in doing good deeds and helping others. 