Kharijah bin Zayd bin Thabit (may Allah have mercy on him) narrates from his father, Sayyiduna Zayd bin Thabit (may Allah be pleased with him), that he said: On the day of Yamamah, many of those who recited the Qur'an were martyred; he mentioned about four hundred. I came to Abu Bakr (may Allah be pleased with him) and said to him: If another battle takes place, the Qur'an will be lost (from people's hearts). Abu Bakr (may Allah be pleased with him) said: "I will not do something that the Messenger of Allah (peace and blessings be upon him) did not do." Then he sent for Umar bin al-Khattab (may Allah be pleased with him), and he said the same: We will not do something that the Messenger of Allah (peace and blessings be upon him) did not do. Zayd bin Thabit (may Allah be pleased with him) said: I said: Then what harm is there for you in it? They both said: There is no harm for us; you have spoken the truth. So Abu Bakr (may Allah be pleased with him) had it written on palm stalks and the shoulder blades of camels.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4824