From Sahih Bukhari (Hadith 3815):
Narrated `Ali:I heard Allah's Messenger (ﷺ) saying (as below) Narrated `Ali: The Prophet (ﷺ) said, "The best of the world's women is Mary (at her lifetime), and the best of the world's women is Khadija (at her lifetime)
Reference: Bukhari 3815