Shaykh ’Uthaymeen, may Allaah have mercy on him, said:
“When they see a person sinning, many brothers hate the sin and this is something correct, but they [also] hate the sinner, and then they deal with him harshly as someone who hates him would, like someone who wants to take revenge on him, and this is a huge mistake.
You must cure the sinner as a gentle doctor who treats a wound in order for it to heal does, he doesn’t treat the wound in order for it to get worse, so he treats this person with gentleness and a desire for good for him and out of mercy for him … this is how the scholars who nurture are, they look at the creation with a view to reform, not to seek revenge and out of hatred—I hate the sin which this person does, but this person is a believer so he is my brother, even if he fornicated and stole, he is still my brother, the believers are but brothers.”
[Majmoo’ Fataawaa wa Rasaa’il Fadilatish-Shaikh Muhammad ibn Saalih al-’Uthaimeen, vol. 27, pp. 311-312]