It was narrated that Ibn Az-Zubair said:"Whoever wields a weapon and starts to strike (the people) with it, it is permissible to shed his blood."
أَخْبَرَنَا أَبُو دَاوُدَ، قَالَ حَدَّثَنَا أَبُو عَاصِمٍ، عَنِ ابْنِ جُرَيْجٍ، عَنِ ابْنِ طَاوُسٍ، عَنْ أَبِيهِ، عَنِ ابْنِ الزُّبَيْرِ، قَالَ مَنْ رَفَعَ السِّلاَحَ ثُمَّ وَضَعَهُ فَدَمُهُ هَدَرٌ .
Nesai
The Book of Fighting [The Prohibition of Bloodshed] • Hadith 4099