Another thing that angered them was when King David said that many of his generation would suffer greatly and die for the sanctification of God's name. The Lord said to him that their sacrifices were not in vain, for their blood was more precious to Him than sacrifices. Rabbi Yehudah said in the name of Rabbi Idi that suffering was divided into three parts: one part was taken by the ancestors and all generations, one part by the generation of the destruction of the Temple, and one part by the generation of the Messiah.
What did the generation of the destruction of the Temple do? They would bring iron balls and flatten them under their breasts, giving up their lives for the sanctification of God's name. And they would also bring reeds and put them under their fingernails, and in this way, they died for the sanctification of God's name.