Musnad Ahmad 33:237

Hassan narrated to us, Zuhair narrated to us, from Abu al-Zubayr, from Jabir, who said: We used to practice *mukhabarah* (sharecropping) during the time of the Messenger of Allah, peace and blessings of Allah be upon him, and we would obtain [a portion] from the *qasri* (the produce of the main part of the land) and from such and such. He said: "Whoever has land, let him cultivate it, or let his brother cultivate it; otherwise, let him leave it."