mam al-Sadiq (as) said (about Abu bakr and Umar): “They are two Imams Adel (Just) and Qasit (Balanced), they were upon the right, and died upon it, so may Allah’s mercy be upon them on the Day of Judgment.”
Here is the full text:
كتاب نفحات اللاهوت : نقلا من كتاب المثالب لابن شهرآشوب ، أن الصادق عليه السلام سئل عن أبي بكر وعمر ، فقال : كانا إمامين قاسطين عادلين ، كانا على الحق وماتا عليه ، فرحمة الله عليهما يوم القيامة ، فلما خلا المجلس ، قال له بعض أصحابه : كيف قلت يا بن رسول الله ؟ ! . فقال : نعم ، أما قولي : كانا إمامين ، فهو مأخوذ من قوله تعالى : * ( وجعلناهم أئمة يدعون إلى النار ) * ، وأما قولي قاسطين ، فهو من قوله تعالى : * ( وأما القاسطون فكانوا لجهنم حطبا ) * ، وأما قولي عادلين ، فهو مأخوذ من قوله تعالى : * ( الذين كفروا بربهم يعدلون ) * ، وأما قولي كانا على الحق ، فالحق علي عليه السلام ، وقولي : ماتا عليه ، المراد أنه لم يتوبا عن تظاهرهما عليه ، بل ماتا على ظلمهما إياه ، وأما قولي : فرحمة الله عليهما يوم القيامة ، فالمراد به أن رسول الله صلى الله عليه وآله ينتصف له منهما ، آخذا من قوله تعالى : * ( وما أرسلناك إلا رحمة للعالمين )
An opponent (Sunni) asked Imam Jaffar as-Sadiq and said: O Allah’s apostle son what do you say about Abu Bakr and Umar? He replied: They are two Imams Adel (Just) and Qasit (Balanced), they were upon the right, and died upon it, therefore may Allah’s mercy be upon them on the Day of Judgment. When the people left, a man from his retinue (Shia) said: O Allah’s apostle son I’m wondering from what you have said about Abu Bakr and Umar! He replied: yes they are two Imams calling for hellfire as Allah said And We made them Imams who call to the fire (28:41) The Qasit as Allah almighty said And as for those who are unjust (Qasit – in this context means unjust), they are firewood for hell (72:15) and the Adel that because they switched from the right as Allah almighty said Yet those who disbelieve ascribe (Ya`diloon) rivals unto their Lord (6:1). What I meant by this was that they were upon the right in that they seized the right of the Commander of Believers (Ali). What I meant by they died upon it that they died was on enmity without repentance. What I meant with mercy be upon them that the mercy is Allah’s apostle because he was a mercy to mankind and he will be a rival for them on the Day of Judgment.
Source: Bihaar al-Anwaar, Volume 30, Page 286, Hadith #150