At the age of eighteen, Guru Nanak Sahib Ji, was sent by his father Bhai Mehta Kalu Ji to the city to do business. His father was disappointed that Guru Sahib's mind was not into farming and other worldly work, therefore, he thought perhaps engaging him in trade would firstly, be a good profitable profession, and secondly his son would be happy all day talking to his clients about his business.
Thinking this way and choosing an auspicious day, he called Bhai Mardana Ji to accompany Guru Sahib.
Pita Kalu Ji gave twenty rupees to Guru Nanak and Bhai Mardana Ji and said, "Go with Nanak. Buy and bring some genuine goods by selling of which we may make profit. In this way if you make a profitable transaction, next time I will send you with more money to buy goods."
Guru Nanak and Bhai Mardana Ji started from Talwandi towards Choohar-khaana to purchase some merchandise. They had hardly gone ten or twelve miles from the village when they came across a village, where the people were thirsty, hungry and sick due to lack of water and an outbreak of disease. Guru Nanak Sahib Ji said to Bhai Mardana Ji, "Father has asked us to carry out some profitable transaction. No bargain can be more truly profitable than to feed and clothe the needy. I cannot leave this true bargain. It is seldom that we get an opportunity to carry out some profitable transaction like this."
Guru Nanak took all the money to the next nearest village dwelling, where he bought plentiful supply of food and brought water for these people. Guru Sahib invested the twenty rupees into what we today call "Langar."
eis bhaekh ai thhaavahu gireho bhal aa jithhahu ko varas aae ||
"Instead of wearing these beggar's robes, it is better to be a householder, and give to others." (Guru Granth Sahib, Ang 587)
As well as bringing food and water to the villagers, Bhai Mardana Ji and Guru Sahib brought clothes for with the money that was left. Taking leave from the villagers, they started back 'empty-handed'.
When both reached near Talwandi, Guru Nanak said to Mardana Ji, 'You go to the village alone, I shall sit at this well." Bhai Mardana Ji went to the village and narrated the whole story to Pita Mehta Kalu Ji. He told him where Guru Nanak was sitting. Mehta Kalu was very angry that they had wasted money on feeding, clothing and taking care of needy people and didn't make any profit. Putting aside all work he took Bhai Mardana Ji along and started towards the well. Guru Nanak Dev asked his father not to get angry with him. He tried to convince his father by telling that he had not done anything wrong with the money but has done a 'Sacha Sauda' ( True bargain) in the true sense.
At the place where the true bargain took place, Gurdwara Sacha Sauda Sahib is built. In current day Pakistan the Gurdwara Sacha Sauda is in the city of Farooqabad.
Doing good to the people is the way of a Sikh. Sharing with the needy, makes the day of a Sikh. The true bargain of life is sharing one's earning with the needy and helping in whatever way we can