What is the ruling on watching pornography?

It is not permissible for a Muslim to watch pornographic films, and he must stay away from them and from anything that calls to them, as Allah Almighty says: "Tell the believing men to reduce [some] of their vision and guard their private parts. That is purer for them. Indeed, Allah is Acquainted with what they do." and "And tell the believing women to reduce [some] of their vision and guard their private parts." Watching them leads to hardness of heart, heedlessness of Allah, and the commission of indecencies.