Sunan Ibn Majah 413
سنن ابن ماجه#413SahihIt was narrated that Shaqiq bin Salamah said:"I saw `Uthman and `Ali performing ablution, washing each part three times, and they said: 'This is how the Messenger of Allah used to perform ablution.'" (Hasan) Another chain with similar wording
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
Shuaib Al ArnautHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 1:147