Musannaf Ibn Abi Shayba 13:3136

Abu Bakr narrated to us, he said: Abu Bakr al-Hanafi narrated to us, from al-Dahhak bin Uthman, he said: Al-Zuhri commanded me, so I wrote a document for him that he borrowed a known amount of gold for a known amount of food, for a known term, from the good food of such-and-such, or its purchase.