Qur'an, Hadith and Scholars:Forbidden Things
Qur'an
Displaying your beauty and ornaments
And say to the believing women that they should lower their gaze and guard their modesty; that they should not display their beauty and ornaments except what (must ordinarily) appear thereof; that they should draw their veils over their bosoms and not display their beauty except to their husbands, their fathers, their husband's fathers, their sons, their husbands' sons, their brothers or their brothers' sons, or their sisters' sons, or their women, or the slaves whom their right hands possess, or male servants free of physical needs, or small children who have no sense of the shame of sex; and that they should not strike their feet in order to draw attention to their hidden ornaments. And O ye Believers! turn ye all together towards Allah, that ye may attain Bliss.
Pork and other non-halal foods
Forbidden to you (for food) are: dead meat, blood, the flesh of swine, and that on which hath been invoked the name of other than Allah; that which hath been killed by strangling, or by a violent blow, or by a headlong fall, or by being gored to death; that which hath been (partly) eaten by a wild animal; unless ye are able to slaughter it (in due form); that which is sacrificed on stone (altars); (forbidden) also is the division (of meat) by raffling with arrows: that is impiety. This day have those who reject faith given up all hope of your religion: yet fear them not but fear Me. This day have I perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion. But if any is forced by hunger, with no inclination to transgression, Allah is indeed Oft-forgiving, Most Merciful.
Gambling, Idol worship and worship by arrows
Intoxicants and gambling, (dedication of) stones, and (divination by) arrows, are an abomination,- of Satan's handwork: eschew such (abomination), that ye may prosper.
Hadith
Grave worship
A'isha reported: Umm Habiba and Umm Salama made a mention before the Messenger of Allah of a church which they had seen in Abyssinia and which had pictures in it. The Messenger of Allah said: When a pious person amongst them (among the religious groups) dies they build a place of worship on his grave, and then decorate it with such pictures. They would be the worst of creatures on the Day of judgment in the sight of Allah.
Bending of water skins
Narrated Abu Said Al-Khudri: Allah's Apostle forbade the bending of the mouths of water skins for the sake of drinking from them.
Cauterization
Narrated Ibn 'Abbas:The Prophet said, "Healing is in three things: cupping, a gulp of honey or cauterization, (branding with fire) but I forbid my followers to use cauterization (branding with fire)."
Changing anything made by Muhammad
Narrated 'Asim al-Ahwal: I saw the drinking bowl of the Prophet with Anas bin Malik, and it had been broken, and he had mended it with silver plates. That drinking bowl was quite wide and made of Nadar wood, Anas said, "I gave water to the Prophet in that bowl more than so-and-so (for a long period)." Ibn Sirin said: Around that bowl there was an iron ring, and Anas wanted to replace it with a silver or gold ring, but Abu Talha said to him, "Do not change a thing that Allah's Apostle has made." So Anas left it as it was.
Dates and syrups
Narrated Abu Qatada: The Prophet forbade the mixing of ripe and unripe dates and also the mixing of dates and raisins (for preparing a syrup) but the syrup of each kind of fruit should be prepared separately. ( One may have such drinks as long as it is fresh )
Killing of tied animals
Narrated Ibn 'Umar:that he entered upon Yahya bin Said while one of Yahya's sons was aiming at a hen after tying it. Ibn 'Umar walked to it and untied it. Then he brought it and the boy and said. "Prevent your boys from tying the birds for the sake of killing them, as I have heard the Prophet forbidding the killing of an animal or other living thing after tying them."
Laughing at Farts
Narrated 'Abdullah bin Zam'a: The Prophet forbade laughing at a person who passes wind, and said, "How does anyone of you beat his wife as he beats the stallion camel and then he may embrace (sleep with) her?" And Hisham said, "As he beats his slave"
Meat of donkeys
Narrated Anas bin Malik: Someone came to Allah's Apostle and said, "The donkeys have been (slaughtered and) eaten. Another man came and said, "The donkeys have been destroyed." On that the Prophet ordered a caller to announce to the people: Allah and His Apostle forbid you to eat the meat of donkeys, for it is impure.' Thus the pots were turned upside down while the (donkeys') meat was boiling in them.
Meat of animals with fangs
Narrated Abu Tha'laba:Allah's Apostle forbade the eating of the meat of beasts having fangs.
Saffron
Narrated Ibn 'Umar: The Prophet forbade Muhrims to wear clothes dyed with Wars or saffron.
Silk
Narrated Hudhaifa: The Prophet said, "Do not drink in gold or silver utensils, and do not wear clothes of silk or Dibaj, for these things are for them (unbelievers) in this world and for you in the Hereafter."
Two Marriages within Two families at the same Time
Narrated 'Abdullah: Nafi narrated to me that 'Abdullah said that Allah's Apostle forbade the Shighar. I asked Nafi', "What is the Shighar?" He said, "It is to marry the daughter of a man and marry one's daughter to that man (at the same time) without Mahr (in both cases); or to marry the sister of a man and marry one's own sister to that man without Mahr." Some people said, "If one, by a trick, marries on the basis of Shighar, the marriage is valid but its condition is illegal." The same scholar said regarding Al-Mut'a, "The marriage is invalid and its condition is illegal." Some others said, "The Mut'a and the Shighar are permissible but the condition is illegal."
Tuft of Hair on Shaven Heads
Narrated (Abdullah) bin 'Umar : Allah's Apostle forbade Al-Qaza' (leaving a tuft of hair here and there after shaving one's head.)
Urinating in Stagnant Water
Jabir reported: The Messenger of Allah forbade to urinate in stagnant water.
Wearing one Garment and Exposing Genitals
Narrated Abu Huraira: The Prophet had forbidden: (A) the Mulamasa and Munabadha (bargains), (B) the offering of two prayers, one after the morning compulsory prayer till the sun rises, and the others, after the 'Asr prayer till the sun sets (C) He also forbade that one should sit wearing one garment, nothing of which covers his private parts (D) and prevent them from exposure to the sky; (E) he also forbade Ishtimal-as-Samma'.