He—may Allah have mercy on him—was asked:

May the working partner in a profit-sharing investment cover his own living expenses from the capital owner’s funds, whether at home or while travelling? If so, may he indulge in fine food and other luxuries at its expense, or must he restrict himself to his customary needs?

He replied:

Praise be to Allah, Lord of all worlds. If they have agreed on a stipulation concerning living expenses, that is permissible. Likewise, if there is an established custom among them and the contract leaves the matter unspecified, it is interpreted according to that custom.

Without either of these, however, it is not permissible. Some scholars hold that he is entitled to living expenses without qualification, even if he has not stipulated this. This is the view of Abū Hanīfa and Mālik, and one opinion of al-Shāfi‘ī. The well-known view is that he is not entitled to living expenses under any circumstances, even if he stipulates them. Whenever he is entitled to living expenses, these must remain within reasonable and customary bounds. Any indulgence beyond those bounds is charged to his own account.