Sahih Muslim Book 31, Hadith Number 6168.

Chapter : It is forbidden to revile the companions of the Holy Prophet (may peace be upon him).

Abu Sa’id reported there was some altercation between Khalid b. Walid and Abd al-Rahman b. ‘Auf and Khalid reviled him. Thereupon Allah’s Messenger (may peace be upon him) said: None should revile my Companions. for if one amongst you were to spend as much gold as Uhud, it would not amount to as much as one mudd of one of them or half of it.