Musnad Abu Ya'la al-Mawsili 109:39

Harun narrated to us, Muhammad bin Salamah al-Harrani narrated to us, he said: Muhammad bin Ishaq informed me—or informed us—from Muhammad bin Yahya bin Habban, from his paternal uncle Wasi’ bin Habban, from Jabir bin Abdullah: The Messenger of Allah (may Allah bless him and grant him peace) commanded that from every harvest of dates, ten wasqs be set aside, with a cluster hung in the mosque for the poor.