Musnad Ahmad 33:850

Muhammad ibn Ja'far narrated to us, Sa'id narrated to us, Matar narrated to us, from 'Ata', from Jabir ibn 'Abdullah, that the Prophet (peace and blessings of Allah be upon him) said: "Whoever has land, let him cultivate it. If he is unable to do so, let him let his brother cultivate it. Otherwise, let him leave it fallow and not rent it out."