Abd Khayr reported,
I heard Ali 
saying from the pulpit, "Shall I tell you who is the best of this nation after its Prophet?" He then mentioned Abu Bakr.Then he said, "Shall I tell you who is the second?" He then mentioned Umar .Then he said, "If I wished, I could inform you of the third." Then he fell silent, and we understood that he meant himself.I asked him, "Did you yourself hear him say this?"He replied, "Yes, by the Lord of the Kaabah, otherwise may I be struck dumb."
Ahmad 909
Sahihحدثنا عبد الله بن عون حدثنا مبارك بن سعيد أخو سفيان عن أبيه عن حبيب بن أبي ثابت
عن عبد خير الهمداني قال
سمعت عليا رضي الله عنه يقول على المنبر ألا أخبركم بخير هذه الأمة بعد نبيها قال فذكر أبا بكر ثم قال ألا أخبركم بالثاني قال فذكر عمر رضي الله عنه ثم قال لو شئت لأنبأتكم بالثالث قال وسكت فرأينا أنه يعني نفسه فقلت أنت سمعته يقول هذا قال نعم ورب الكعبة وإلا صمتا
Its isnad is sahih. Abdullah bin Awn bin Abu Awn Hilali Admi is thiqah and trustworthy, and he is among the teachers of Muslim and of Abdullah bin Ahmad. I did not find any explicit statement that Ahmad narrated from him, even though Ahmad praised him and spoke well of him. But this is how the hadith appears in (ك) and (ح), from Ahmad from him, while in (ه) it is presented as a narration of Abdullah bin Ahmad from Abdullah bin Awn, which would make it one of the additions.Mubarak bin Saeed is the brother of Sufyan Thawri, and he is thiqah. Abu Saeed bin Masruq Thawri is thiqah.As for his statement, "or else let them be deaf," he means his ears. He referred the pronoun back to them without mentioning them explicitly, since that is understood from the context. He is invoking deafness upon them if he was not truthful in claiming that he heard. The one who asked and the one who answered were Habib bin Abu Thabit and Abd Khayr, or else Abd Khayr and Ali. This hadith is a longer version of the one preceding it. The more correct view is that this is one of the additions of Abdullah, as we explained at 2886.