Muhammad b. Abi Umair narrates – I asked Imam Sadiq: Why did Ameerul Momineen Ali
(a.s.) not fight against his opponents in the very beginning?
Imam (a.s.) replied: It was due to the verse of the Book of Allah, had they been widely separated one from another, We would surely have punished those who disbelieved from among them with a painful punishment. (Surah Fath (48): 25)
(i.e. Ameerul Momineen (a.s.) did not fight until the time the believers were born from the progeny of disbelievers)