Jami` at-Tirmidhi 3707
جامع الترمذي#3707SahihNarrated Ibn 'Umar:"While the Messenger of Allah (ﷺ) was alive, we used to say: 'Abu Bakr, and (then) 'Umar, and (then) 'Uthman
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih Bukhari
In-book reference: 49:103