Musnad Ahmad 30:1840

'Affan narrated to us, he said: Wuhayb narrated to us, Suhayl narrated to us, from his father, from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "Indeed, one of you gives in charity a date from pure earnings, and he places it in its proper place, so Allah takes it with His Right Hand. Then it does not cease to grow, as one of you raises his foal, until it becomes like the mountain, or greater than the mountain."