Rules of Mudarabah Between the Worker and the Owner of the Capital

Question:
I have money in a bank. Is it permissible for me to agree with the bank to make this money a mudarabah between me and them, so that I get half the profit and they get half, and if there is a loss, the loss is also shared equally? What is the solution and the practice in this matter?

Answer:
In a mudarabah, the worker does not bear the loss. The worker is a partner in the profit, and the loss is upon the owner of the capital, because it is a trust in the worker's hand, provided that the worker did not neglect or fall short. The loss is upon the owner of the capital, and the profit is shared by half, or a quarter, or a third, if it is in a known commodity. If it is in a bank with known commodities, they put it in specific cars, they put it in houses, in farms, by half, by a third, by a quarter.
This is a mudarabah. He must fear Allah in it, take care of it, not fall short in it, and preserve it. If profit comes, it is between them according to the condition. If no profit comes, the loss is upon the owner of the capital. This is if it is pure. However, the people of banks and the people of riba are not to be trusted; they may mix it with other things. He should do this with non-riba-dealing people, with non-riba-dealing banks, with sound individuals, so that he is safe that his money has not been handled by one who deals in riba.

Question : Well, what if he agreed with the bank on the loss?

Answer: A condition that contradicts [the ruling] is not valid.