The grandfather of Ibn al-Hakam bin Amr al-Ghifari said: I was with Sayyiduna al-Hakam bin Amr al-Ghifari (may Allah be pleased with him) when the messenger of Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) came to him and said: Sayyiduna Ali (may Allah be pleased with him) says that you are the most deserving of those who should help us in this matter. Al-Hakam (may Allah be pleased with him) said: I heard my intimate friend, your cousin (peace and blessings be upon him), saying: "When the matter becomes like this, or similar to this, I should take a sword of wood." So I have taken a sword of wood.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3145