Sunan an-Nasa'i 1451
سنن النسائي#1451SahihUbaidullah bin 'Abdullah bin Umar narrated that:His father said: "The Messenger of Allah (ﷺ) prayed two rak'ahs in Mina, and Abu Bakr prayed two rak'ahs, and Umar prayed two rak'ahs, and Uthman prayed (two rak'ahs) at the beginning of his Khilafah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Bukhari
In-book reference: 15:19