Musannaf Ibn Abi Shayba 13:2331

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from ‘Awf, from Ibn Sirin, regarding the *mudarib* (the entrepreneur in a profit-sharing partnership): If he makes a profit, then incurs a loss, then makes a profit, he said: The accounting is based on the initial capital, unless there was, prior to that, a taking possession of the wealth or an accounting by way of taking possession.