Sahih Muslim Book 31, Hadith Number 6116.

Chapter : Allah’s Apostle (may peace be upon him) invoked blessings upon the tribes of Ghifar and Aslam.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: To the tribe of Aslam Allah has granted safety and to the tribe of Ghifar Allah has granted pardon. Verily it is not I that say this, but (it is) Allah the Exalted and Glorious. (who) says this.