Praise be to Allah.
Those who are fasting and other Muslims should fear Allaah with regard to what they do and what they refrain from doing at all times, and they should beware of that which Allaah has forbidden of watching indecent movies which show things which Allaah has forbidden, such as pictures of naked and semi-naked people and evil words; the same applies to things that appear on TV which go against the laws of Allaah, such as images, songs, musical instruments and misleading advertisements.
Every Muslim, whether he is fasting or not, should be beware of playing with cards, because of what that involves of witnessing evil and doing evil, and because it also leads to hard-heartedness, sickness in the heart and lack of respect for Allaah’s laws and finding what Allaah has made obligatory to be burdensome, such as praying in congregation and other obligatory duties, and falling into many haraam things. Allaah, may He be exalted, says (interpretation of the meaning):
“And of mankind is he who purchases idle talks (i.e. music, singing) to mislead (men) from the path of Allaah without knowledge, and takes it (the path of Allaah, or the Verses of the Qur’aan) by way of mockery. For such there will be a humiliating torment (in the Hell‑fire).
7. And when Our Verses (of the Qur’aan) are recited to such a one, he turns away in pride, as if he heard them not — as if there were deafness in his ear. So announce to him a painful torment”
And Allaah says in Soorat al-Furqaan, describing the slaves of the Most Merciful (interpretation of the meaning):
“And those who do not bear witness to falsehood, and if they pass by some evil play or evil talk, they pass by it with dignity”
Falsehood includes all kinds of evil, and what is meant by “[they] do not bear witness” is that they are not present. The Prophet (peace and blessings of Allaah be upon him) said: “There will be among my ummah people who regard adultery, silk, alcohol and music as permissible.” Narrated by al-Bukhaari in his Saheeh in a mu’allaq, majzoom report. What is meant by music is singing and musical instruments. Allaah has forbidden to the Muslims the means that cause them to fall into evil. Undoubtedly watching evil films and the evils that are shown on television are means that cause one to fall into evil or to become careless and not denounce it. And Allaah is the One whose help we seek. End quote.
Majmoo’ Fataawa al-Shaykh Ibn Baaz (15/315).
These sins detract from the reward of fasting, and may erase it altogether.
See also the answer to question no. 50063.