I want to know what is forbidden from the Muslim when he is fasting.
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
All the things that are prohibited for a non-fasting person are more emphatically prohibited for a fasting person. There are other things that are forbidden only for the fasting person because they can invalidate his fast. These are:
1) Eating or drinking intentionally without being mistaken or compelled, whether to eat or drink nourishing or non-nourishing items in the daytime of Ramadan (or any day of fasting); Allah Says (what means): {And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until the sunset.} [Quran 2:187]
But as for the person who has done these things unintentionally, the Prophet said: “Allah has forgiven those deeds which were done mistakenly, or in a state of forgetfulness, or in compulsion.” [Ibn Maajah, Al-Tabaraani and by Al-Haakim]
2) Intentionally vomiting, as the Prophet said: “He who could not endure vomiting does not have to make up the fasting, but whoever intentionally vomits has to make up that day.” [Ahmed, Abu Daawood, At-Tirmithi and others]
3) Having sexual intercourse between a husband and his wife. This is because the Prophet instructed the man who had sex with his wife in Ramadan to expiate. But to have sexual intercourse with someone other than one’s wife is forbidden, and also invalidates the fast.
4) Masturbation: Which means: to try to satisfy one’s sexual desire intentionally, whether by using one’s hand or by other means, or by wife dalliance (if this causes the sperm to come out). All scholars of Islam agree upon the above.
5) Failing to make the intention of fasting. The Prophet said: “Indeed, deeds are judged according to their intentions.” [Al-Bukhari and Muslim]
There are other things that are prohibited for the fasting and the non-fasting person during Ramadan and at other times as well, that do not spoil the fast, such as: backbiting, tale-bearing, looking at things that Allah has forbidden such as: women photos, films that show unveiled (women), mixing of the sexes, …
To conclude, the fasting person should know that fasting is not limited only to avoiding eating, drinking and having intercourse; but the real fast is that where all organs fast from that which Allah has forbidden. The Prophet said: “Whoever does not eschew false statements, acting according to them, and ignorance, Allah has no need that he should abstain from his food and his drink.” [Al-Bukhari]
Besides, Jabir ibn ‘Abdullah said: “If you fast, let your hearing and sight fast, and be sober and calm. Do not harm the neighbors and do not make your fasting day and non-fasting day the same.”
Allah knows best.
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