Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Umair that a slave was given permission by his master to supply goods, and another slave was given permission to dye. Hazrat Shurayh made both of them guarantors: the tailor was made guarantor for the supply and the needle, and the other was made responsible for the wage of dyeing, and likewise for anything similar to these tasks.

Hazrat Ibn Sirin says that if a slave is given permission for any specific type of business and he engages in trade of a different type, then there is no liability (debt) upon him.

Hazrat Hasan bin Salih says that if a slave is sent for work in only one category, then he is permitted to do so.