Ali (a.
Ali (a.s.) and Umar were of opposite temperaments and friendship is not possible between people of such opposite temperaments. In such a condition, Umar could not make Ali (a.s.) the Caliph and he considered himself becoming the Caliph against hidden wisdom. So he apparently made Abu Bakr the Caliph and gave him oath of allegiance. Though Umar had no military exploits to his credit, as seen in the battles of Badr, Uhud, etc. it is true that he had cunning for political manipulations.
He made Abu Bakr the Caliph after great manipulations. First of all, this action distanced Bani Hashim from kingdom. Secondly, the appointment of Abu Bakr was actually the appointment of Umar as the Caliph. Thirdly, this course of action served as a defense of his selfishness. Fourthly, due to the old age of Abu Bakr, it was clear that the time of Umar’s Caliphate was not far off. Thus, within a period of two years Abu Bakr made Umar the Caliph and left the mortal world.
History shows that since the time of passing away of the Holy Prophet (S) till the time he himself died, Umar continued to make political machinations, but Ali (a.s.) did not resort to any such machinations. Whenever the Caliph’s court was held, he reiterated his rights and kept silent. But the separation from government was very sorrowful for Bani Hashim. But when Abu Bakr was declared the Caliph, they became sad and kept quiet and were not able to do anything.
The reason was that Ali (a.s.) did not resort to violence at the appointment of Abu Bakr as the Caliph. Apart from this, Bani Hashim had hopes that Ali (a.s.) was young and after sometime he would surely become the Caliph, but their hopes were dashed when Abu Bakr made Umar the Caliph by bequest. Indeed, the appointment of Umar as Caliph by Abu Bakr was an act of returning the favor. Now the Bani Hashim were certainly distanced from rulership.
Since Umar was not aged like Abu Bakr there was no hope that the seat of Caliphate would fall vacant in near future. Umar occupied the seat of Caliphate for ten and a half years. If he had not been killed, he might have continued for another ten years at the helm of affairs. But these ten years were not in any way less for Bani Hashim and the fact is that even after these ten years, Ali (a.s.) was not able to gain the seat of Caliphate.
Before his death, Umar left the appointment of Caliph an undecided matter. It was a political trick by which Ali (a.s.) had very remote chances of success.