Riyad as-Salihin

Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "The faithful and diligent slave will have a double reward." (Abu Hurairah added:) By Him in Whose Hand the soul of Abu Hurairah is! but for Jihad in the Cause of Allah, and Hajj and kindness to my mother, I would have preferred to die as a slave.

[Al-Bukhari and Muslim].