Sahih al-Bukhari 85
Sahih al-Bukhari · Book 3: Knowledge · Whoever gave a religious verdict by beckoning or by nodding
Narrated Abu Huraira:
حَدَّثَنَا الْمَكِّيُّ بْنُ إِبْرَاهِيمَ ، قَالَ أَخْبَرَنَا حَنْظَلَةُ بْنُ أَبِي سُفْيَانَ ، عَنْ سَالِمٍ ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " يُقْبَضُ الْعِلْمُ، وَيَظْهَرُ الْجَهْلُ وَالْفِتَنُ، وَيَكْثُرُ الْهَرْجُ ". قِيلَ يَا رَسُولَ اللَّهِ وَمَا الْهَرْجُ فَقَالَ هَكَذَا بِيَدِهِ، فَحَرَّفَهَا، كَأَنَّهُ يُرِيدُ الْقَتْلَ.
The Prophet (ﷺ) said, "(Religious) knowledge will be taken away (by the death of religious scholars) ignorance (in religion) and afflictions will appear; and Harj will increase." It was asked, "What is Harj, O Allah's Messenger (ﷺ)?" He replied by beckoning with his hand indicating "killing." (Fath-al-Bari Page 192, Vol. 1)