Qur’an:

“And say not of that, which your tongues lyingly claim: “This is lawful and this is forbidden (Haram)!” So that you invent lies about God. For those, who invent lies against God, it will not be pleasant for them.” [An-Nahl 16:116]

ولا تقولوا لما تصف ألسنتكم الكذب هذا حلال وهذا حرام لتفتروا على الله الكذب إن الذين يفترون على الله الكذب لا يفلحون

Sunnah:

Ali Ibn Ibrahim Al-Qummi writes: “It refers to that, which the Jews used to say: ‘What is in the wombs of these animals, is reserved for the men among us (6:139), but declared forbidden (Haram) for our wives.” [Tafsir Al-Qummi, Vol. 1 page 391]

قال أبو الحسن القمي: قال عز وجل ولا تقولوا لما تصف ألسنتكم الكذب هذا حلال وهذا حرام لتفتروا على الله الكذب قال هو ما كانت اليهود يقولون ما في بطون هذه الانعام خالصة لذكورنا ومحرم على ازواجنا

Abd-ur-Rahim Al-Qasir reported that Imam As-Sadiq (a) said: “If a servant commits one of the major or one of the minor sins, that God has forbidden for him, then by this he will leave the position of belief (Iman) and will lose the title of being a believer (Mu’min), while the title of being a submitter (Muslim) will still apply for him. If he repents and asks for forgiveness, then he will be returned to the realm of belief (Iman), from which nothing will bring him to disbelief (Kufr) except for denying and judging with regard to that which is permissible, saying about that which is permissible: “That is forbidden (Haram)!” And saying about that which is forbidden: “That is permitted!” And from this he derives his religion from, thereby leaving from the submission (Islam) and belief (Iman) and turning to disbelief (Kufr). He is like the one, who enters into the state of consecration and thereupon enters the house of worship, wherein something happens and he leaves the house of worship and the state of consecration, so that his neck is struck and he becomes a dweller in the Hellfire.” [Al-Kafi of Al-Kulaini, Volume 2 page 27 – 28 Hadith 1]

علي بن إبراهيم، عن العباس بن معروف، عن عبد الرحمن بن أبي نجران عن حماد بن عثمان، عن عبد الرحيم القصير عن أبي عبد الله الصادق عليه السلام قال: فإذا أتى العبد كبيرة من كبائر المعاصي أو صغيرة من صغائر المعاصي التي نهى الله عز وجل عنها كان خارجا من الايمان، ساقطا عنه اسم الايمان وثابتا عليه اسم الاسلام فان تاب واستغفر عاد إلى دار الايمان ولا يخرجه إلى الكفر إلا الجحود والاستحلال أن يقول للحلال: هذا حرام وللحرام: هذا حلال ودان بذلك فعندها يكون خارجا من الاسلام والايمان، داخلا في الكفر وكان بمنزلة من دخل الحرم ثم دخل الكعبة وأحدث في الكعبة حدثا فاخرج عن الكعبة وعن الحرم فضربت عنقه وصار إلى النار

Abu Basir reported that he asked Imam As-Sadiq (a.) about the verse: “They took their scholars and their monks to be lords besides God.” (9:31) He said: “By God, they did not directly call upon them, to worship them, for if they had called upon them to do so, they would not have obeyed them in that, but they declared the forbidden (Haram) to be permissible (Halal) and declared the permissible (Halal) to be forbidden (Haram) to them. Therefore, they worshipped them in a way, by which they did not realise it.” [Al-Fusul of Al-Amili, Volume 1 page 524 Hadith 1]

محمد بن يعقوب، عن عدة من أصحابنا، عن أحمد بن محمد بن خالد، عن عبد الله بن يحيى، عن ابن مسكان، عن أبي بصير، عن أبي عبد الله عليه الصلاة والسلام قال: قلت له: اتخذوا أحبارهم ورهبانهم أربابا من دون الله فقال: أما والله ما دعوهم إلى عبادة أنفسهم ولو دعوهم ما أجابوهم ولكن أحلوا لهم حراما وحرموا عليهم حلالا فعبدوهم من حيث لا يشعرون

Ja’far As-Sadiq (a.) reported that Prophet Muhammad (s.) said: “I cursed seven persons, and God curses them and it is fulfilled by every Prophet.” One said: “Who are these, O Messenger of God?” He said: “The one, who adds in the Book of God, the one, who denies the destiny of God, the one, who contradicts my custom (Sunnah), the one, who allows towards my family, that which God has declared forbidden, the one, who takes possesion by force, to dignify someone, whom God humiliated and to give a low position to him to whom God gave a high position, he who usurps the booty of Muslims which was acquired without fighting, while deeming that permissible and he who declares something forbidden (Haram) that which God declared permissible (Halal).” [Al-Wasa’il of Al-Amili, Volume 16 page 51 Hadith 17]

عن جعفر الصادق عليه السلام عن النبي صلى الله عليه وآله قال: إني لعنت سبعا لعنهم الله وكل نبي مجاب قيل: ومن هم يا رسول الله؟ قال: الزائد في كتاب الله، والمكذب بقدر الله، والمخالف لسنتي، والمستحل من عترتي ما حرم الله، والمسلط بالجبروت ليعز من أذل الله ويذل من أعز الله والمستأثر على المسلمين بفيئهم منتحلا  له والمحرم ما أحل الله عز وجل