Musnad Ahmad 27:1920

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from al-Zuhri, from Salim, from Ibn 'Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever sells a slave, his wealth belongs to the seller, unless the buyer stipulates [otherwise]. And whoever sells date palms that have fruit which has been pollinated, their fruit belongs to the seller, unless the buyer stipulates [otherwise]."