Musnad Ahmad 27:1017

Yazid narrated to us, Muhammad informed us, from Nafi’, from Ibn Umar, who said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) forbidding the sale of *habal al-habalah* (the offspring of the offspring). That is because the people of the Jahiliyyah (pre-Islamic era) used to conduct that sale, so he forbade them from that.