Musannaf Ibn Abi Shayba 13:1136

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Ibn ‘Awn, from Muhammad, that he used to dislike *al-qatru*. Ibn ‘Awn said: *Al-qatru* is when a man sells to a man, and he adds something of weight to the containers.