Sunan Ibn Majah 95
سنن ابن ماجه#95Da'ifIt 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Zubair Ali ZaiDaif