Musnad Abu Ya'la al-Mawsili 108:194

Zakariya ibn Yahya narrated to us, Hushaym narrated to us, from Khalid, who said: Some of our elders narrated to us from Jabir ibn Abdullah, that Abu Bakr said: "Whoever has a promise from the Messenger of Allah (may Allah bless him and grant him peace), let him stand up." He said: So I said, "The Messenger of Allah (may Allah bless him and grant him peace) promised me that he would give me such and such," and he scooped with his hand three scoops. He said: So Abu Bakr said, "If wealth comes to us, then come to us." He said: Then wealth came to him, so I came to him. He said: "Scoop it with your hand." I did so, and he said: "Count it." It was five hundred. He said: "Then he gave me another thousand." He said: And he said, "Do you have any wealth other than it?" I said, "No." He said, "Then when a year passes over it, pay its Zakat."