Making Fun of the Righteous

Question :

What is the ruling on mocking those who adhere to the orders of Allâh and His Messenger?

Answer:

Mocking those who adhere to the orders of Allah and His Messenger, if it is because they are adhering to that, then it is unlawful and constitutes a grave sin for one who does it. This is because it is feared that his dislike for them is a dislike for what they follow, for their steadfast adherence to Allah's religion. In this case, when the mocking is of the way they follow, then they are like the people Allâh mentioned:
"If you ask them, they declare: "We were only talking idly and joking." Say: "Was it at Allah Almighty, and His Verses, and His Messenger that you were mocking?" Make no excuse; you have disbelieved after you had believed."

This verse was revealed about some of the hypocrites who said, "We have not seen anyone who is equal to our reciters (the Messenger of Allah and to his Companions), in their desire for food, in the lies of their tongues, and in their cowardice on the battlefield." So Allâh revealed this verse about them.

Let those who mock the people of truth because they are religious people beware, for Allah Almighty said:
"Verily! Those who committed crimes used to laugh at those who believed. And whenever they passed by them, used to wink one to another; and when they returned to their own people, they would return jesting, and when they saw them, they said: "Verily! These have indeed gone astray!" But they had not been sent as watchers over them. But this Day those who believe will laugh at the disbelievers. On thrones, looking (at all things). Are not the disbelievers paid (fully) for what they used to do?"

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 8 Pages 361-362