Omar ibn al Khattab
Upon accession to the Caliphate, Abu Bakr (r) was faced with several crises. The immediate issue was the dispatch of the army to the north to face the Byzantines. The Muslims had faced a stalemate with the Byzantines at the Battle of Tabuk and had lost their leader Zaid bin Haris. A follow up defensive expedition had been initiated by the Prophet to safeguard the northern approaches to Madina. Abu Bakr (r) reaffirmed the decision of the Prophet and dispatched an expedition under Usama bin Zaid. The expedition was successful and it demonstrated the strength and cohesiveness of the Muslims even in the absence of the Prophet.
The second challenge was the refusal of certain Arab tribes to pay the Zakat. Pre-Islamic Arabia was tribal. Many of these tribes had reluctantly accepted Islam towards the last days of the Prophet. When he passed away, they saw an opportunity to stop paying the mandatory Zakat, which they misunderstood as another form of taxation.
Zakat is not only a moral obligation in Islam; it is also a legal obligation. It is an act of purity. It is regarded as one of the five pillars of Islam and is an article of faith. In Islam, the economic well being of the community is as important as that of the individual. No man’s belief is complete unless he wishes for his brother what he wishes for himself. Islam discourages hoarding and encourages sharing and investment. Zakat works to circulate money and operates against hoarding. Wherever the Qur’an emphasizes the establishment of prayer, it also emphasizes the payment of Zakat. Foregoing Zakat would have destroyed the moral foundation of the Islamic state and would have reduced Islam to a litany of personal beliefs and observances. Abu Bakr (r) conducted a vigorous police action against the non-payers of Zakat. He personally went on several expeditions and brought the rebellious tribes under the authority of the state.
The third crisis faced by Abu Bakr (r) was that of false prophets. Seeing the success and prosperity of the Muslims, many false prophets (and prophetesses) sprang up all over Arabia. Religion was and remains to this day, good business. Many a pretender saw in the success of Islam an opportunity to establish his own religion and get rich in the process. Abu Bakr (r) declared war on the false prophets. He sent eleven expeditions against as many pretenders. Of these the best known was the expedition of Khalid bin Walid against Musailimah al Kazzab, which culminated in the Battle of Yamama. Similar expeditions were sent towards Yemen, Amman and Hazeefa. All of these expeditions were successful.