The sincere Muslim seeks to perfect his worship in a way that pleases Allah The Almighty. Here are some of the acts that reduce the reward of the fasting people in the noble month of Ramadan.
Looking at women who expose their beauty
Q: Does going out to run some errands and coming across indecently dressed women during the day in Ramadan invalidate one's fast?
A: This does not invalidate the fast, however, one should lower his gaze as much as possible.
[Permanent Committee for Fatwa no. 6364]
Q: Does looking at women and beardless young boys affect your fast?
A: Yes, every sin affects one's fast, for Allah The Almighty decreed fasting for us to become righteous. Allah The Almighty Says (what means): {O you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous} [Quran 2:183].
The Messenger of Allah said: "Whoever does not give up false statements (i.e. telling lies), acting upon them and ignorance, Allah will not be in need of his (fasting) leaving his food and drink." [Al-Bukhari]
We ask Allah The Almighty to cure the man who suffers from this affliction, as he is undoubtedly committing something forbidden, as a gaze is an arrow of Satan – we seek refuge with Allah The Almighty.
Looking at forbidden things repeatedly gives rise to confusing thoughts in people’s hearts, causing a person to become captivated by them. Many are the gazes that have affected men’s hearts until they became captive.
This is why when someone is afflicted with this habit (indulging in forbidden gazes), he should turn to Allah The Almighty in repentance, while supplicating Him to cure him. He should also abstain from directing his eyesight to any woman or any young man without a beard. If he abides by seeking the help of Allah The Almighty, seeking refuge in Him and asking Him to cure him from this disease, he will be cured, Allah willing.
[Shaykh Ibn ‘Uthaymeen: Al Fataawa]
He kissed a non-Mahram (marriageable) girl in Ramadan
Q: What is the ruling on a man who kissed a non-Mahram girl in Ramadan? Does he have to make up for the day?
A: A man who kissed a non-Mahram girl has certainly failed to fulfill the obligations of fasting, as he has committed a sinful act while fasting. The Messenger of Allah said: "Whoever does not give up false speech and acting upon it, and ignorance (evil action), Allah has no need of him giving up his food and drink." [Al-Bukhari]
If he compelled her to do so (to allow him to kiss her), then he has committed both a sinful act and an act of ignorance. His fast has no doubt lost its meaning and his reward is diminished.
However, according to the majority of scholars, this does not invalidate his fast, which means that he is not obliged to make up for the day.
The questioner should counsel the person who committed this act, and urge him to repent to Allah The Almighty. This act is forbidden, since it makes the heart incline towards created beings and forget the remembrance of Allah The Exalted, which can be the cause of a great affliction.
[Shaykh Ibn ‘Uthaymeen: Al Fataawa]
Insult and abuse from the fasting person
Q: If someone gets angry at something and he scolds and insults others, does this invalidate his fast?
A: This does not invalidate his fast, but it does diminish his reward. The Muslim should control his temper and safeguard his tongue from insulting, abusing, backbiting, tale-bearing and other such acts forbidden by Allah The Almighty, whether while fasting or at any other time. However, during fasting, one should take particular care to avoid these acts, as this is more important and perfects his fast. It is also takes one further away from harming people that may be a cause for afflictions, grudges and disunity. The Messenger of Allah said: "If one of you is fasting, he should avoid sexual relations with his wife and quarreling, and if somebody fights or quarrels with him, he should say, 'I am fasting.'" [Al-Bukhari and Muslim]
[Permanent Committee for Fatwa no.7825]
Uttering obscene words because of a traffic jam
Q: Due to the severe traffic jam, some people utter obscene words that may reach the extent of insulting and abusing others while driving their cars and fasting in Ramadan. What is the ruling on their fast?
A: Concerning their fast, it is valid as forbidden acts and words do not invalidate fasting, but they certainly reduce its reward and waste its benefits and fruits.
The intended purpose of fasting is to become righteous as Allah The Exalted Says (what means): {O you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous} [Quran 2:183].
Allah The Almighty clarified the wisdom of imposing fasting upon us, which is to become righteous and fear Him.
The Messenger of Allah said: "Whoever does not give up false statements (i.e. telling lies), acting upon them, and intolerance, Allah will not be in need of his (fasting) leaving his food and drink."
Furthermore, the Prophet said that if somebody fights or quarrels with a fasting person, he should say, "I am fasting". This would deter the one who insults the fasting person and let him know that he did not abstain from answering him back because he was unable to do so, but because he fears Allah The Almighty, as he is fasting. It is incumbent upon those who are fasting as well as those who are not to be patient and tolerant and not be provoked by things that he does not like.
A man said to the Prophet “Advise me, O Messenger of Allah!” The Prophet said: “Do not get angry.” He repeated that more than once: “Do not get angry.”
People inevitably regret their actions while they are angry and wish they had not said or done something in a fit of rage, but such things can never be undone.
[Shaykh Saalih Al-Fawzaan: Kitaab Ad-Da‘wah]