Praise be to Allah.
The scholars set a rule that says that in principle everything is permissible, and they based this rule on shar‘i evidence.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
It should be understood that in principle all things, of various types and categories, are generally halaal for human beings, and that they are taahir (pure) and it is not forbidden for people to handle them and touch them. This is a comprehensive rule that is general in application, and it is an important ruling that is of immense benefit and brings much blessing, and the scholars turned to it when issuing ruling on innumerable actions and issues faced by people. It is based on by ten points of evidence – from what I can call to mind of sources of sharee‘ah – namely: the Book of Allah, the Sunnah of His Messenger, and following the path of the believers that is mentioned in the verses (interpretation of the meaning): “Obey Allah and obey the Messenger (Muhammad (blessings and peace of Allah be upon him)), and those of you (Muslims) who are in authority” [an-Nisa’ 4:59] and “Verily, your Walee (Protector or Helper) is Allah, His Messenger, and the believers” [al-Maa’idah 5:55]; in addition to qiyaas (analogy), consideration, rational thinking, and insight.
End quote from Majmoo‘ al-Fataawa (21/535)
Then he (may Allah have mercy on him) quoted the evidence for that, so please refer to the book mentioned above.
What this ruling means is that with regard to everything that is of benefit on earth, and what man may attain thereof, making use of it is permissible, so long as there is no evidence to indicate that it is prohibited.
With regard to food, drink, clothing and soap (and cleaning materials), this rule is to be followed with regard to everything concerning which there is no shar‘i text, with the exception of the following:
Things containing any considerably harmful ingredients, because the basic principle with regard to harmful substances is that they are prohibited, and they are not included in the rule that in principle everything is permissible.
Allah, may He be exalted, says (interpretation of the meaning):
“and do not throw yourselves into destruction” [al-Baqarah 2:195]
“And do not kill yourselves (nor kill one another). Surely, Allah is Most Merciful to you” [an-Nisa’ 4:29].
It was narrated from Abu Sa‘eed al-Khudri (may Allah have mercy on him) that the Prophet (blessings and peace of Allah be upon him) said: “There should be neither harming nor reciprocating harm.” Narrated by al-Haakim (2/57-58). He said: Its isnaad is saheeh according to the conditions of Muslim. It was also classed as saheeh by al-Albaani in Silsilat al-Ahaadeeth as-Saheehah (1/498)
The mufassir Shaykh Muhammad al-Ameen ash-Shanqeeti (may Allah have mercy on him) discussed this issue and said:
If it is purely harmful with no benefit at all, then it is haraam, because the Prophet (blessings and peace of Allah be upon him) said: “There should be neither harming nor reciprocating harm.”
If it is beneficial in some ways and harmful in others, then one of three scenarios must apply:
1. Either the benefit outweighs the harm
2. or the converse is true
3. or the benefit and harm are equal.
If the harm outweighs the benefit or is equal to it, then it is not allowed, because of the hadith, “There should be neither harming nor reciprocating harm,” and because warding off harm takes precedence over achieving interests.
If the benefit outweighs the harm, then the most correct view is that it is permissible, because it is a well-established principle that greater benefits take precedence over lesser harms.
End quote from Adwa’ al-Bayaan (7/793-794)
The basic principle with regard to meat is that it is prohibited.
That is because it is not permissible to eat meat unless it is slaughtered in the proper manner, fulfilling all the necessary conditions.
Al-Khattaabi (may Allah have mercy on him) said:
With regard to anything that is haraam in principle, it only becomes permissible if it fulfils the necessary conditions and is done in the proper manner, such as intimate relationships, which do not become permissible until after marriage. Similarly, the meat of sheep does not become permissible unless it is slaughtered in the proper manner. If there is any doubt concerning the fulfilment of these conditions, and whether they were met for certain in the manner that indicates that it has become permissible, then the original principle remains in effect and the meat is prohibited.
End quote from Ma‘aalim as-Sunan (3/57)
But in order to prove that it is permissible, it is sufficient to know that the one who slaughtered it was a Muslim or one of the People of the Book (a Jew or Christian). After that it is not necessary to ascertain the method of slaughter for each animal, as has been explained previously in fatwa no. 223005 .
Based on that, with regard to meat that is available in a Muslim or Christian country, it is deemed to be permissible, unless it is proven in our view that it was slaughtered by a method that is contrary to Islamic rulings, such as strangling or electric shock, or that the name of Allah was not mentioned over it, and so on.
With regard to products for which there is no shar‘i evidence that they are prohibited, or the list of ingredients does not include any components that are prohibited or are harmful, then we rule that it is permissible and pure, and that basic principle is not altered for mere doubts or unproven talk.
But if prohibited ingredients are included in some food, is it prohibited to consume it altogether? This is subject to further detailed discussion, as has been explained in fatwa no. 114129.
To sum up: if the prohibited substance is still present in its original form, then it is haraam to consume it.
But if it has been transformed into another substance by means of interactions or manufacturing processes, and the first prohibited substance is no longer present in its original form, then the more correct scholarly view is that it is permissible to consume it.
With regard to clothing, it comes under the rule that in principle everything is permissible. The basic principle concerning it is that it is permissible, except what is excluded by Islamic rulings, such as silk which is prohibited for men, and some animal skins that cannot be purified by means of tanning. That has been explained previously in fatwa no. 1695 .
And Allah knows best.