Works : Islamic Laws
199. Any liquor which becomes vinegar by itself, or by mixing it with vinegar or salt, becomes Pak.
200. Wine which is prepared from najis grapes etc., or if any external najasat reaches it, would not become Pak, if it turns into vinegar.
201. Vinegar which is prepared from najis grapes, raisins and dates is najis.
202. If tiny stems and stalks from grapes or dates are added, and then vinegar is poured over it, or, if cucumber and brinjal is added before it turns into vinegar, there will be no harm, except if it becomes an intoxicant, before becoming vinegar.
203. If the juice of grapes ferments by itself, or when heated, it becomes haraam. However, if it boils so much that only 1/3 part of it is left, it becomes halal. And it has already been mentioned in rule 114 that the juice of grapes does not become najis on fermentation.
204. If 2/3 of the grape juice gets reduced without fermentation, and the remainder ferments, and if it is commonly held as grape juice and not as syrup, it will be haraam, as an obligatory precaution.
205. The juice of grapes, about which it is not known whether fermentation has taken place or not, is halal. But if it ferments, then it will not be halal till 2/3 of it is gone.
206. If, for example, there are some ripe grapes in a bunch of unripe grapes, and the juice of that bunch is not commonly known as "grape juice", it will be halal even if it ferments.
207. If one grape falls in something which is boiling with heat, and if it ferments, but does not get dissolved in it, eating that grape alone will be haraam.
208. If juice of grapes is being cooked in several pots, it is permissible to use the same spoon for the pot which has boiled, and the one which has not.
209. A thing, about which one does not know whether it is unripe grapes or ripe grapes, will be halal if it ferments.