The Messenger of Allah ﷺ was the best of people in character.
كان رسول الله ﷺ أحسن الناس خلقا.
No references are available.
Bukhari narrated it in al-Adab (6203) and Muslim in al-Fadail (55:2310), both through the route of Abdul-Warith, from Abu Tayah, from Anas, who mentioned it. There are many hadiths on this subject, and they are mentioned in the book on the biography of the Prophet ﷺ.