Musannaf Ibn Abi Shayba 13:2514

Abu Bakr narrated to us, he said: Ibn Numayr narrated to us, from Sufyan, from 'Asim, from Ibn Sirin, regarding a man who hires a boatman on the condition that the loss is upon him [the boatman] and the surplus is for him [the boatman]. He said: The surplus is for the owner of the food, and the loss is upon the boatman.