Refuting an allegation about Abu Bakr fighting those who refused to pay Zakah
1-4-2013 | IslamWeb
Question:
Why did Abu Bakr, may Allaah be pleased with him, fight those who refused to pay Zakaah although the Prophet, sallallaahu ‘alayhi wa sallam, said: "I forbid the killing of those who offer the prayers"?It is also reported in a Hadeeth that Khaalid ibn Al-Waleed, may Allaah be pleased with him, said to the Prophet, sallallaahu ‘alayhi wa sallam, about the first to appear of the Khawaarij, "Should I behead him? The Prophet, sallallaahu ‘alayhi wa sallam, said to him, "No, perhaps he offers the prayers." Khaalid, may Allaah be pleased with him, exclaimed saying, "Many are those who pray and say with their tongues that which their hearts are devoid of." The Messenger of Allaah, sallallaahu ‘alayhi wa sallam, replied saying: "I was not commanded to explore the hearts of people or to split open their bellies." This means that the blood of the father of the Khawaarij was not declared violable by the Prophet, sallallaahu ‘alayhi wa sallam, because he offered prayer. Moreover, none of the Muslims advised Abu Bakr, may Allaah be pleased with him, to fight those people but they even objected to his decision to do so at first. There is variance in the opinions of Muslim jurists regarding the ruling on killing a Muslim who refuses to pay Zakaah as long as he says the testimony of truth and offers the prayers.
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Abu Bakr 
fought those who refused to pay Zakah basing his decision on the consensus of the Companions 
. Consensus is a decisive truth in the religion of Allaah The Almighty, a great fundamental of the religion and a source of the Sharee‘ah. Al-Qhaadhi Abu Ya‘la 
said: "Consensus is a decisive proof that should be applied and it is impermissible to act contrary to it. It is impossible that the Ummah has a consensus on error."
We do not mean by this that consensus takes precedence over the texts of the Quran and Sunnah. Rather, the consensus is construed from them and comes next to them in status. We mean that the forbiddance made by the Prophet, sallallaahu ‘alayhi wa sallam, to kill those who offer the prayers is not of a general indication since the apostate is to be killed even if he does not abandon the prayer. This is also supported by the fact that the one who offers the prayers may be killed by way of retribution, as a corporal punishment for committing adultery if he is married or if he previously married or in case he transgresses and wages war and other similar cases where killing is reported to be the relevant corporal punishment regardless of whether the person offers the prayers or not.
This specification of the indication of the Hadeeth is construed by Abu Bakr as he said: "By Allaah, surely I will fight whoever separates prayer and Zakah, for indeed Zakah is the right pertaining to money. By Allaah, if they withhold from me a rope which they used to pay to the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, I will fight them for it."
This is also what ‘Umar understood from the Hadeeth when he heard the words of Abu Bakr so he said, "By Allaah! No sooner had I seen that Allaah The Almighty Expanded Abu Bakr's breast for this decision than I knew that it was the truth." [Al-Bukhari and Muslim]