Violating the rights of others pollutes the mind.
Always be honest, ever be kind.

Guru Nanak Dev stayed with Bhai Lalo when he began his preaching missions. Bhai Lalo was a carpenter who earned his living honestly by working hard all day. The local village official was a corrupt person. He was known as Malik Bhago. One day Malik Bhago invited every resident of the village to a feast so he could impress them with his wealth. Guru Nanak Dev declined to attend. Special messengers were sent to bring him. Bhago offered delicious food to the Guru, and, in response to his offer, waited for good words from him. Guru Nanak Dev, rather than praising Malik Bhago, declined to accept any food from him. Bhago was surprised to hear a refusal for the delicious food and he immediately asked the reason for the refusal.

The Guru told him that the food which Malik Bhago considered to be tasty and sweet was, in fact, made from the blood of the poor. Malik Bhago had been extracting money from the people instead of living by honest means. Bhago was very much embarrassed by the bold and frank comments of the Guru. Everyone else appreciated the truth fearlessly spoken by Guru Nanak Dev. Bhago could not deny the allegations made against him in the presence of the respectable people of the village. Faced with the obvious, Malik Bhago confessed his guilt. He requested to be pardoned for his past deeds and he promised to live a true and honest life in the future.

Guru Nanak Dev then told the gathering that Bhai Lalo's honestly earned food, no matter how bland, tasted good and sweet like milk. Malik Bhago's dishonestly earned food, no matter how rich and luxurious, was akin to drinking the blood of the innocent. If drops of blood fall on a cloth, it becomes dirty. How can the mind of a person who lives on the blood of the helpless remain pious and clean?

Violating the rights of others is a sin. Personal gains made in this way are poisonous to one's character.