What evidence establishes the existence of a deposit (Wadiah)?

Primary text

A deposit is established only by the admission of the deceased or their heirs, or by valid testimony (Bayyinah). Finding a document marked 'deposit' on the deposited item is not sufficient proof against the heirs because the writing could pertain to a previous deposit or a transaction where the deceased purchased the item. Similarly, finding a note stating 'So-and-so has a deposit with me' in the father's papers does not bind the heir, as the deceased might have returned it and forgotten to remove the writing.