What is the ruling on a person's disposal of money deposited with him and trading with it without the owner's permission and consent, even though the depositor became wealthy because of it?

He who invests money entrusted to him without the owner's permission has committed something unlawful or reprehensible. Scholars differ concerning the ruling on the profit generated from such an investment. Some held that the profit belongs to the trustee and the loss is borne by him. This is the view of the Malikis, based on the principle of "gain accompanies liability." Others held that the profit belongs to the owner of the entrusted property, and the trustee's actions are like those of an usurper. This is the view of the Hanbalis.