Busr bin Saeed reported,
Uthman bin Affan 
called for water and performed ablution near the benches, washing each part three times. He then asked the Companions of the Messenger of Allah ﷺ, "Did you see the Messenger of Allah ﷺ do this?"They replied, "Yes."Ubayy said, this man al-Adani was in Makkah and served as the scribe dictating the narrations of Ibn Uyayna.
Ahmad 488
Sahihحدثنا عبد الله بن الوليد حدثنا سفيان حدثني سالم أبو النضر
عن بسر بن سعيد
عن عثمان بن عفان رضي الله عنه أنه دعا بماء فتوضأ عند المقاعد فتوضأ ثلاثا ثلاثا ثم قال لأصحاب رسول الله ﷺ هل رأيتم رسول الله ﷺ فعل هذا قالوا نعم قال أبي هذا العدني كان بمكة مستملي ابن عيينة
No references are available.
Its chain of transmission is sahih. At the end, Ahmad's words describe his teacher Abdullah bin Walid, who is trustworthy. He narrated from Sufyan Thawri. Ibn Adi said, "He narrated Thawri's Jami from him." Harb reported from Ahmad, "He heard from Sufyan, and he used to verify his hearing, but he was not a hadith specialist. His hadith is sahih, though he would sometimes make mistakes in names." Daraqutni said, "Trustworthy, reliable."This hadith is a shortened version of the one before it. It appears in Majma al-Zawaid 1:228-229, where it is said, "Ahmad narrated it, and the hadith of Uthman is in the Sahih, and the men of this narration are the men of the Sahih."