Musannaf Ibn Abi Shaybah

Hazrat Tawus disliked that a person should sell ghee and olive oil in such a way that he reduces something in exchange for the container and says that this is as per weight. (For example, he weighs the container and the contents inside it against one hundred kilograms, then reduces ten grams from the hundred on the basis that it is the weight of the container.)

Muhammad, may Allah have mercy on him, disliked "qatar". Hazrat Ibn Aun says that "qatar" is when a person sells to another and sets aside a portion of the weight for the container.

22394 - Ibn ‘Awn said: (And) (1) al-Qatr: a man sells to another man and adds something to the weight for the sake of circumstances.

Hazrat Ibn Sirin was asked that people sell goods in containers and put a certain known quantity in them in exchange for the container? He, may Allah have mercy on him, replied: Sell by the full weight, and the container will be included with it. (When weighing, the container will be counted along with it.)

Hazrat Qatadah and Hazrat Abu Hashim were asked whether a person may sell ghee or honey in such a way that he adds a certain amount in exchange for the container, so they disliked doing so.

Ibrahim (may Allah have mercy on him) was asked about a Bedouin who brought a container of ghee and sold it in such a way that he would put some nails in exchange for the container. He (may Allah have mercy on him) said: There is no harm in doing so.