It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that once someone asked the Holy Prophet (peace and blessings be upon him): "Which deed is the most virtuous?" The Holy Prophet (peace and blessings be upon him) replied: "To have faith in Allah." The questioner asked: "Then which deed is most virtuous?" He replied: "Jihad in the way of Allah." The questioner asked: "After that?" He replied: "A Hajj that is accepted (by Allah)."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7641