It says in Tehillim that “One who speaks falsehood will not stand before my eyes!” and they are amongst the four groups of people who will not receive the visage of the Divine Presence. Chazal also said that anyone who lies is considered as if he had served idols.
One of the special characteristics of Klal Yisrael is that they do not lie, as it says “The remnant of Yisrael will not commit iniquity not speak deceit and in their mouths will not be found expressions of falsehood!”. One who has this bad trait of saying lies has transgressed that which the Torah says “You must keep far away from a matter of falsehood!” and his punishment is great as about no other sin does the Torah use an expression saying that one must keep far away from it. In addition to this, he is a shameful person and disgusted by the people as even the other nations “Whose mouths speak falsely and their right hand is a false right hand!” have people amongst them who are very careful never to lie as common sense sees and knows that it is something disgusting, hated and abominated and the punishment of a liar is that even when he tells the truth no-one believes him as he has acquired a bad name for himself that he never tells the truth. In direct contrast to this, one who speaks only the truth acquires a good name for himself.
The Midrash says as a parable that Falsehood married Loss (damage and loss of property) and therefore everything which falsehood gains is destroyed and lost.
Itt is obvious that anyone who lies in his business will see no signs of blessing and even if he will have a blessing temporarily he is “Making wealth when it is not just, it will abandon him in half of his days!”. There is wealth which is kept to harm its owners and when forbidden money becomes mixed with permissible money the permissible money will also be lost.