Abdur Razaq San'ani (Died 211 AH) narrated a lengthy narration in which Abbas and Ali Ibn Abi Talib (as) went to 'Umar to resolve a dispute upon which 'Umar told them like this :
......فلما قبض رسول الله صلى الله عليه وسلم قال أبو بكر: أنا ولي رسول الله صلى الله عليه وسلم بعده، أعمل فيه بما كان يعمل رسول الله صلى الله عليه وسلم فيها. ثم أقبل على علي والعباس فقال: وأنتما تزعمان أنه فيها ظالم فاجر والله يعلم أنه فيها صادق بار تابع للحق، ثم وليتها بعد أبي بكر سنتين من إمارتي، فعملت فيها بما عمل رسول الله صلى الله عليه وسلم وأبو بكر وأنتما تزعمان أني فيها ظالم فاجر،.....
.....When Messenger of Allah (swt) died Abu Bakr said : I am Wali (Sucessor) of Messenger of Allah (swt) after him, I will do the way he used to do. Then Umar faced towrads Ali and Umar and told them : You both used to believe him (Abu Bakr) to be Oppressor and Sinfull. I swear by Allah, He was truthfull and follower of Right path in that and After Abu Bakr i became Wali (Sucessor) for 2 years and i did the same what Prophet (ﷺ) and Abu Bakr used to do and you two believe me to be a Oppressor and Sinfull.....
Now the samw narration has been quoted by Ahmad bin Hanbal (Died 241 AH) from Abdur Razaq San'ani but he cropped out the part in which Umar is saying that Ali and Abbas used to believe Abu Bakr and Umar are Oppressors and Sinfull persons.