Even an outwardly respectable activity may be pursued for a harmful purpose. Earning, trading, reputation, and position should therefore be considered in light of intention and others’ rights.
For example, one shopkeeper seeks more customers by improving quality and pricing honestly; that is permissible effort. Another makes false claims to raise sales; the method is wrongful.
خَطِيئَةٍ means a mistake or sin. Linking it to رَأْس, the image of a leading cause, directs attention to the harm generated by uncontrolled desire.