the latter of which was partially based on their certainty of the righteousness of their cause. Additionally, the general belief among the Muslims was that the community must be defended at all costs. Historian Theodor Nöldeke gives the somewhat controversial opinion that this religious fervour was intentionally used to maintain the enthusiasm and momentum of the ummah: Though Abu Bakr had started these initial conflicts which eventually resulted in the Islamic conquests of Persia and the Levant, he did not live to see those regions conquered by Islam, instead leaving the task to his successors. Preservation of the Quran Abu Bakr was instrumental in preserving the Quran in written form. It is said that after the hard-won victory over Musaylimah in the Battle of Yamama in 632, Umar saw that some five hundred of the Muslims who had memorised the Quran had been killed. Fearing that it may become lost or corrupted, Umar requested that Abu Bakr authorise the compilation and preservation of the scriptures in written format. The caliph was initially hesitant, being quoted as saying, "how can we do that which the Messenger of Allah, may Allah bless and keep him, did not himself do?" He eventually relented, however, and appointed Zayd ibn Thabit, who had previously served as one of the scribes of Muhammad, for the task of gathering the scattered verses. The fragments were recovered from every quarter, including from the ribs of palm branches, scraps of leather, stone tablets and "from the hearts of men". The collected work was transcribed onto sheets and verified through comparison with Quran memorisers. The finished codex, termed the Mus'haf, was presented to Abu Bakr, who prior to his death, bequeathed it to his successor Umar. Upon Umar's own death, the Mus'haf was left to his daughter Hafsa, who had been one of the wives of Muhammad. It was this volume, borrowed from Hafsa, which formed the basis of Uthman's legendary prototype, which became the definitive text of the Quran. All later editions are derived from this original. Death On 23 August 634, Abu Bakr fell sick and did not recover. He developed a high fever and was confined to bed. His illness was prolonged, and when his condition worsened, he felt that his end was near. Realising this, he sent for Ali and requested him to perform his ghusl since Ali had also done it for Muhammad. Abu Bakr