Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "The righteous and sincere slave has a double reward." By the One in whose hand is the soul of Abu Hurayrah, were it not for jihad in the path of Allah, Hajj, and kindness to my mother, I would have loved to die while still a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15809