Question: In what way was the story of Joseph the best of stories: “We relate to you the best of stories” [Yusuf: 3]?
Answer (and from Allah is success): This can be known if you recognize several matters, as it appears to me:
1. The story of Joseph that Allah related in the Qur’an is undoubtedly a true and truthful story in all its details, because Allah Himself narrated it.
2. It contains admonitions and lessons for believers, doers of good, and all righteous servants of Allah.
3. It contains a sign indicating the truthfulness of the Prophet (May Allah bless him and his family and grant them peace).
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3