The Principles of determining haram (prohibited) and halal (lawful) have been detailed in Surah Araf – 7:33

قُلْ إِنَّـمَا حَرَّمَ رَبِّيَ الْفَوَاحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ وَالإِثْمَ وَالْبَغْيَ بِغَيْرِ الْـحَقِّ وَأَن تُشْرِكُوْا بِاللّهِ مَا لَـمْ يُنَزِّلْ بِهِ سُلْطَانًا وَأَن تَقُولُوْا عَلَى اللّهِ مَا لاَ تَعْلَمُوْنَ

Tell [them]: “My Lord has only forbidden all lewd acts, whether overt or hidden [20] and usurping the rights of others and wrongful oppression [21] and that you worship with Him what He did not sanction [22] and that you fabricate something about God what you know not.”[23] (Quran 7:33)

(Excerpt from Quranic Exegesis: Javed Ahmed Ghamidi)

(Translated by Dr. Shehzad Saleem)

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[20]. Ie., vulgar acts whether committed openly or in secret are forbidden under all circumstances. It is used in the plural so that it includes fornication, homosexuality, bestiality and all other sins of similar nature. The word فَوَاحِشَ comprehensively includes exposing the private parts before others, spreading details of sexual nature or fornication.

[21]. Qualifying the word “oppression” with “wrongful” is meant to portray its heinous nature. It does not mean that there are some types of oppression which are not wrongful. Every type of oppression is wrongful per se. Thus this word is also used to qualify the crime of killing prophets of God.

[22]. This is stated because no argument – whether intellectual, scriptural or natural – in favour of polytheism has ever been presented nor will it ever be presented.

[23]. The actual words are: وَأَن تَقُولُوْا عَلَى اللّهِ مَا لاَ تَعْلَمُوْنَ. It is evident from the preposition after that the verb encompasses a meaning. The actual construction is to the effect: مُفْتَرِيْنَ عَلَی اللّٰهِِ. In other words, if edicts regarding the lawful and unlawful are given on personal preferences, if in accordance with personal desires religious innovations are invented or if shari‘ah directives are fabricated and then ascribed to God – then all these practices come under this expression.