DEPOSIT (Arabic wadi’ah وديعة
pl. wadai’), in the language of the law, signifies a thing entrusted to the care of another. The proprietor of the thing is called mudi’, or depositor; the person entrusted with it is muda’, or trustee, and the property deposited is wadi’ah, which literally means the leaving of a thing with another.
According to the Hidayah, the following are the rules of Islam regarding deposits.
A trustee is not responsible for deposit unless he transgress with respect to it. If, therefore, it be lost whilst it is in his care, and the loss has not been occasioned by any fault of his, the trustee has not to make good the loss, because the Prophet said, “an honest trustee is not responsible.”
A trustee may also keep the deposit himself or he may entrust it to another, provided the person is a member of his own family, but if he gives it to a stranger he renders himself responsible.
If the deposit is demanded by the depositor, and the trustee neglects to give it up, this is a transgression, and the trustee becomes responsible.
If the trustee mix the deposit (as of grain, &c) with his own property, in such a manner that the property cannot be separated, the depositor can claim to share equally in the whole property. But if the mixture be the result of accident, the proprietor becomes a proportionate share in the whole. If the trustee deny the deposit upon demand, he is responsible in case of the loss of it. But not if the denial be made to a stranger, because (says Abu Yusuf) the denial may be made for the sake of preserving it. In the case of a deposit by two persons, the trustee cannot deliver to either his share, except it be in the presence of the other. And when two persons receive a divisible article in trust, each must keep one half, although these restrictions are not regarded when they are held to be inconvenient, or contrary to custom.
Based on Hughes, Dictionary of Islam