Hadith 1456
Narrated Abu Huraira: Abu Bakr said, "By Allah! If they (pay me the Zakat and) withhold even a she-kid which they used to pay during the lifetime of Allah's Apostle, I will fight with them for it."
Hadith 1457
قَالَ
عُمَرُ رَضِيَ اللَّهُ عَنْهُ : فَمَا هُوَ إِلَّا أَنْ رَأَيْتُ أَنَّ اللَّهَ شَرَحَ صَدْرَ أَبِي بَكْرٍ رَضِيَ اللَّهُ عَنْهُ بِالْقِتَالِ فَعَرَفْتُ أَنَّهُ الْحَقُّ " .
Umar said, "It was nothing but Allah Who opened Abu Bakr's chest towards the decision to fight, and I came to know that his decision was right."