It was narrated that 'Ali said:
"The Messenger of Allah said: 'Abu Bakr and 'Umar are the leaders of the mature people of Paradise, and the first and the last, except for the Prophets and Messengers, but do not tell them about that, O 'Ali, as long as they are still alive.'" (ID)
English reference (ID): Vol. 1, Book 1, Hadith 95 (ID)
Arabic reference (ID): Book 1, Hadith 100 (ID)