Musnad Ahmad 830:81

Ubayd Allah ibn Muhammad narrated to us, he said: I heard Hammad ibn Salamah narrating from Ali ibn Zayd, and Humayd, among others, from al-Hasan, from Abu Bakrah, from the Prophet, peace and blessings of Allah be upon him, that he said: "Indeed, Allah will support this religion with people who have no share [of reward] for themselves."