Blood
1. The blood of a human being, and of every animal whose blood gushes forth when its large (jugular) vein is cut, is Najis. The blood of an animal like a fish, or an insect like mosquito, is Tahir because it does not gush forth.
2. If an animal whose meat is lawful to eat, is slaughtered in accordance with the method prescribed by Shari`ah, and enough blood flows out, the blood which is still left in its body is Tahir. However, the blood, which goes back into the body of the animal due to peath, or because of its head having been at a higher level at the time of its slaughtering, is Najis.
3. As a recommended precaution, one should refrain from eating an egg which has even the smallest amount of blood in it. However, if the blood is in the yolk (yellow portion), the albumen (white portion) will be Tahir, as long as the skin over the yolk is not torn.
4. If the blood, which comes from the gums of the teeth, vanish as it gets mixed with the saliva, the saliva is Tahir.
5. If the blood, which dries under the nail or skin, on account of being hurt, can no longer be called blood, it is Tahir. But if it is called blood and is presented on the surface, it will be Najis. Thus if a hole appears in the nail or the skin, and it is difficult to remove the blood and to make it Tahir for the purpose of Ghosl or Ghusl, one should perform Tayammum (ablution with soil).
6. If a person cannot discern whether it is dried blood under the skin, or that the flesh has turned that way because of being hit, it is Tahir.
7. When a wound is healing, and pus forms around it, that substance is Tahir if it is not known to have been mixed with blood.
Dogs and Pigs
Dogs and pigs are Najis, and even their hair, bones, paws and nails, and every liquid substance of their body, is Najis.
Kàfir
A person who does not believe in Allah or his oneness, is Najis. Similarly, ghulat who believe in any of the holy twelve Imàms as God, or that they are incarnations of God, and khawarij and nawasib who express enmity towards the holy Imàms, are also Najis. And similar is the case of those who deny Prophet hood, or any of the necessary laws of Islam, like prayer and fasting, if they result in denying the holy prophet (s). As regards the people of the Scripture (i.e.the Jews, the Christians and the Magian), they are considered Tahir.
Wine
1. Wine is Najis and everything else which in toxicates a person is not Najis.
2. All kinds of industrial alcohol used for painting doors, windows, tables, chairs etc are Tahir.
3. If grape juice ferments by itself, or on being cooked, it is Tahir, but it is Halal (allowed) (unlawful) to drink it. Also, as an obligatorw precaution, boiled grope is Halal (allowed) to eat, but is not Najis.
4. If dates, currants, raisins, or their juice ferment, they are Tahir and it isHalal (allowed) (lawful) to eat them.
5. Beer,which lightly intoxicates, and is called Fuqa, is Halal (allowed), and as an obligatory precaution, is Najis. But barlew juice, which does not intoxicate at all, is Tahir andHalal (allowed).
Source:
A Brief of Islamic Law
The Grand Ayatollah Al-Sistani
[Vol. 1, p. 10-11].
