Musnad Abu Ya'la al-Mawsili 154:192

Suwayd narrated to us, from Malik, from Nafi’, from Ibn ‘Umar, that the Prophet (peace be upon him) forbade *habal al-habalah*. He said: The people of the Jahiliyyah used to trade in it. A man would buy a camel to be delivered when the she-camel gives birth, and then [when] the one in its womb gives birth.