Musnad Ahmad 589:6

'Abd al-Samad narrated to us, Ziyad ibn Muslim Abu 'Umar narrated to us, Abu al-Ash'ath al-San'ani narrated to us, he said: Yazid ibn Mu'awiyah sent us to Ibn al-Zubayr. When I arrived in Medina, I entered upon so-and-so—Ziyad forgot his name—and he said: "The people have done what they have done, so what do you see?" He said: "My intimate friend, Abu al-Qasim (may Allah bless him and grant him peace), advised me: 'If you reach anything of these tribulations, then head to Uhud and break the edge of your sword against it, then sit in your house.'" He said: "If someone enters upon you in the house, then stand up and go to the private chamber. If he enters upon you in the private chamber, then kneel on your knees and say: 'Bear my sin and your sin, so you will be among the companions of the Fire, and that is the recompense of the wrongdoers.' So I have broken the edge of my sword and sat in my house."