Imam Ar-Ridha’ (a.s.) said:
لَيْسَ مِنّا مَنْ غَشَّ مُسْلِماً أَوْ ضَرَّهُ أَوْ ما كَرَهُ
One who defrauds or causes a loss to a Muslim or tricks him, does not belong to us.1
Those who find their happiness in misfortunes of others and their profit in loss of others are neither human nor true Muslims. They lack that social character which gives man superiority over other creatures.
Losses can be inflicted openly or may be hidden through frauds and tricks and other forms of dishonesty. Islam forbids these, whatever the form, as is apparent from the disgust expressed in the above saying of Imam Ar-Ridha’ (a.s.)