Hadith: Don't they forbid what Allah allows, so you forbid it? Don't they allow what Allah forbids, so you allow it? I said: Yes. He said: That is how you worship them

عن عدي بن حاتم رضي الله عنه : "أنه سمع النبي صلى الله عليه وسلم يقرأ هذه الآية: "اتَّخَذُوا أَحْبَارَهُمْ وَرُهْبَانَهُمْ أَرْبَابًا مِنْ دُونِ اللَّهِ وَالْمَسِيحَ ابْنَ مَرْيَمَ وَمَا أُمِرُوا إِلاَّ لِيَعْبُدُوا إِلَهًا وَاحِدًا لا إِلَهَ إِلاَّ هُوَ سُبْحَانَهُ عَمَّا يُشْرِكُونَ" فقلت له: إنا لسنا نعبدهم، قال: أليس يُحَرِّمُونَ ما أحل الله فتُحَرِّمُونَهُ؟ ويُحِلُّونَ ما حَرَّمَ الله فتُحِلُّونَهُ؟ فقلت: بلى، قال: فتلك عبادتهم".
[صحيح] - [رواه الترمذي]

‘Adiyy ibn Hātim (may Allah be pleased with him) reported: I heard the Prophet (may Allah's peace and blessings be upon him) recite this verse: {They have taken their scholars and monks as lords besides Allah, and [also] the Messiah, the son of Mariyam. And they were not commanded except to worship one God; there is no deity except Him. Exalted is He above whatever they associate with Him.} So I said to him: "We do not worship them." He replied: "Don't they forbid what Allah allows, so you forbid it? Don't they allow what Allah forbids, so you allow it?" I said: 'Yes.' He said: "That is how you worship them."
Sahih/Authentic. - [At-Tirmidhi]

Explanation

‘Adiyy ibn Hātim, a noble Companion, heard the Prophet (may Allah's peace and blessings be upon him) recite a verse indicating that the Jews and Christians took their scholars and devout people as deities. They would legislate for them rulings opposite to Allah's legislations and would be obeyed. On hearing the verse, ‘Adiyy could not understand what it means, because he thought that worship was confined to prostration and similar acts. Therefore, the Prophet (may Allah's peace and blessings be upon him) told him that part of worshipping the rabbis and monks lies in obeying them in forbidding the lawful and allowing the forbidden, thus contradicting the divine and prophetic legislation.