He (may Allāh be pleased with him) said, “Zakāt on one’s wealth is an obligation. By Allāh. I will fight anybody who distiguishes betweeen prayer and Zakāt.” ‘Umar said, "I saw nothing other than the fact that Allāh had opened Abū Bakr’s heart to fighting them. Then I knew that he was right.” [Reported by Bukhārī and Muslim 7284]