Musnad Ahmad 30:1253

Uthman ibn Umar narrated to us, he said: Yunus narrated to us, from al-Zuhri, from Sa’id ibn al-Musayyib, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "For the righteous slave who is owned, there are two rewards." By the One in Whose hand is the soul of Abu Hurairah, were it not for Jihad in the way of Allah, and Hajj, and kindness to my mother, I would have loved to die while I was a slave.