Allah said,
﴿لَوْلاَ يَنْهَـهُمُ الرَّبَّـنِيُّونَ وَالاٌّحْبَارُ عَن قَوْلِهِمُ الإِثْمَ وَأَكْلِهِمُ السُّحْتَ لَبِئْسَ مَا كَانُواْ يَصْنَعُونَ ﴾
(Why do not the Rabbaniyyun and the Ahbar forbid them from uttering sinful words and from eating illegal things. Evil indeed is that which they have been performing.) meaning why don't the Rabbaniyyun and the Ahbar forbid them from this evil The Rabbaniyyun are the scholars who are in positions of authority, while the Ahbar are the regular scholars.
﴿لَبِئْسَ مَا كَانُواْ يَصْنَعُونَ﴾
(Evil indeed is that which they have been performing.) referring to the Rabbaniyyun, as `Ali bin Abi Talhah reported from Ibn `Abbas, because they abandoned forbidding evil. Ibn Jarir recorded that Ibn `Abbas said, "There is no Ayah in the Qur'an that has more severe admonition than this Ayah,
﴿لَوْلاَ يَنْهَـهُمُ الرَّبَّـنِيُّونَ وَالاٌّحْبَارُ عَن قَوْلِهِمُ الإِثْمَ وَأَكْلِهِمُ السُّحْتَ لَبِئْسَ مَا كَانُواْ يَصْنَعُونَ ﴾
(Why do not the Rabbaniyyun and the Ahbar forbid them from uttering sinful words and from eating illegal things. Evil indeed is that which they have been performing.)'' Ibn Abi Hatim recorded that Yahya bin Ya`mar said, " `Ali bin Abi Talib once gave a speech, which he started by praising Allah and thanking Him. He then said, `O people! Those who were before you were destroyed because they committed sins and the Rabbaniyyun and Ahbar did not forbid them from evil. When they persisted in sin, they were overcome by punishment. Therefore, enjoin righteousness and forbid evil before what they suffered also strikes you. Know that enjoining righteousness and forbidding evil does not reduce the provision or shorten the term of life.'' Imam Ahmad recorded that Jarir said that the Messenger of Allah said,
«مَا مِنْ قَوْمٍ يَكُونُ بَيْنَ أَظْهُرِهِمْ مَنْ يَعْمَلُ بِالْمَعَاصِي هُمْ أَعَزُّ مِنْهُ وَأَمْنَعُ، وَلَمْ يُغَيِّرُوا إِلَّا أَصَابَهُمُ اللهُ مِنْهُ بِعَذَاب»
(There is no people among whom there are those who commit sins, while the rest are more powerful and mightier than the sinners, yet they do not stop them, but Allah will send a punishment upon them.) Ahmad was alone with this wording. Abu Dawud recorded it, but in his narration Jarir said, "I heard the Messenger of Allah saying,
«مَا مِنْ رَجُلٍ يَكُونُ فِي قَوْمٍ يُعْمَلُ فِيهِمْ بِالْمَعَاصِي، يَقْدِرُونَ أَنْ يُغَيِّرُوا عَلَيْهِ، فَلَا يُغَيِّرُوا إِلَّا أَصَابَهُمُ اللهُ بِعِقَابٍ قَبْلَ أَنْ يَمُوتُوا»
(There is no one who resides among people commiting evil among them, and they do not stop him though they are able to do so, but Allah will punish them ﴿all﴾ before they die.)'' Ibn Majah also recorded this Hadith.
﴿وَقَالَتِ الْيَهُودُ يَدُ اللَّهِ مَغْلُولَةٌ غُلَّتْ أَيْدِيهِمْ وَلُعِنُواْ بِمَا قَالُواْ بَلْ يَدَاهُ مَبْسُوطَتَانِ يُنفِقُ كَيْفَ يَشَآءُ وَلَيَزِيدَنَّ كَثِيراً مِّنْهُم مَّآ أُنزِلَ إِلَيْكَ مِن رَّبِّكَ طُغْيَـناً وَكُفْراً وَأَلْقَيْنَا بَيْنَهُمُ الْعَدَاوَةَ وَالْبَغْضَآءَ إِلَى يَوْمِ الْقِيَـمَةِ كُلَّمَآ أَوْقَدُواْ نَاراً لِّلْحَرْبِ أَطْفَأَهَا اللَّهُ وَيَسْعَوْنَ فِى الاٌّرْضِ فَسَاداً وَاللَّهُ لاَ يُحِبُّ الْمُفْسِدِينَ - وَلَوْ أَنَّ أَهْلَ الْكِتَـبِ ءَامَنُواْ وَاتَّقَوْاْ لَكَفَّرْنَا عَنْهُمْ سَيِّئَـتِهِمْ وَلاٌّدْخَلْنَـهُمْ جَنَّـتِ النَّعِيمِ - وَلَوْ أَنَّهُمْ أَقَامُواْ التَّوْرَاةَ وَالإِنجِيلَ وَمَآ أُنزِلَ إِلَيهِمْ مِّن رَّبِّهِمْ لاّكَلُواْ مِن فَوْقِهِمْ وَمِن تَحْتِ أَرْجُلِهِم مِّنْهُمْ أُمَّةٌ مُّقْتَصِدَةٌ وَكَثِيرٌ مِّنْهُمْ سَآءَ مَا يَعْمَلُونَ ﴾
(64. The Jews say: "Allah's Hand is tied up.'' Be their hands tied up and be they accursed for what they uttered. Nay, both His Hands are widely outstretched. He spends as He wills. Verily, the revelation that has come to you from your Lord makes many of them increase in rebellion and disbelief. We have put enmity and hatred among them till the Day of Resurrection. Every time they kindled the fire of war, Allah extinguished it; and they (ever) strive to make mischief on the earth. And Allah does not like the mischief-makers.) (65. And if only the People of the Scripture had believed and had Taqwa, We would indeed have expiated for them their sins and admitted them to Gardens of pleasure (in Paradise).) (66. And if only they had acted according to the Tawrah, the Injil, and what has (now) been sent down to them from their Lord (the Qur'an), they would surely have gotten provision from above them and from underneath their feet. And among them is a Muqtasid Ummah, but for most of them; evil is their work.)