Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 3127
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.