Narrated Abu Huraira:

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 Apostle?" He replied by beckoning with his hand indicating "killing." (Fath-al-Bari Page 192, Vol. 1)

حَدَّثَنَا الْمَكِّيُّ بْنُ إِبْرَاهِيمَ، قَالَ أَخْبَرَنَا حَنْظَلَةُ بْنُ أَبِي سُفْيَانَ، عَنْ سَالِمٍ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ، عَنِ النَّبِيِّ ﷺ قَالَ " يُقْبَضُ الْعِلْمُ، وَيَظْهَرُ الْجَهْلُ وَالْفِتَنُ، وَيَكْثُرُ الْهَرْجُ ". قِيلَ يَا رَسُولَ اللَّهِ وَمَا الْهَرْجُ فَقَالَ هَكَذَا بِيَدِهِ، فَحَرَّفَهَا، كَأَنَّهُ يُرِيدُ الْقَتْلَ.