Sahih Muslim Book 7, Hadith Number 3127.

Chapter : The merit of Hajj and Umra and the day of ‘Arafa (the 9th of Dhu’l-Hijja).

Abu Huraira (Allah be pleased with him) reported Allah’s Messenger (may peace be upon him) as saying: An Umra is an expiation for the sins committed between it and the next, and Hajj which is accepted will receive no other reward than Paradise.