Imam Hasan b. Ali b. Abi Talib (a.s.) relates – When Umar was facing death, he said, ‘I repent to Allah for the following three actions: 1- Abu Bakr and I took the rule over the people from others; 2- I forced the caliph on the people; 3- I ranked some people over others.
Al-Khesaal chapter 3 trad 225